diff --git a/lib/ex_doc/config.ex b/lib/ex_doc/config.ex
index 670c14b75..a259edc1e 100644
--- a/lib/ex_doc/config.ex
+++ b/lib/ex_doc/config.ex
@@ -3,6 +3,7 @@ defmodule ExDoc.Config do
 
   # Defaults
   @default_source_ref "main"
+  def default_group_for_doc(metadata), do: metadata[:group]
   def filter_modules(_module, _metadata), do: true
   def before_closing_head_tag(_), do: ""
   def before_closing_footer_tag(_), do: ""
@@ -21,6 +22,7 @@ defmodule ExDoc.Config do
             before_closing_head_tag: &__MODULE__.before_closing_head_tag/1,
             canonical: nil,
             cover: nil,
+            default_group_for_doc: &__MODULE__.default_group_for_doc/1,
             deps: [],
             extra_section: nil,
             extras: [],
@@ -63,15 +65,16 @@ defmodule ExDoc.Config do
           before_closing_head_tag: (atom() -> String.t()) | mfa() | map(),
           canonical: nil | String.t(),
           cover: nil | Path.t(),
+          default_group_for_doc: (keyword() -> String.t() | nil),
           deps: [{ebin_path :: String.t(), doc_url :: String.t()}],
           extra_section: nil | String.t(),
           extras: list(),
           filter_modules: (module, map -> boolean),
           formatter: nil | String.t(),
           formatters: [String.t()],
-          groups_for_extras: keyword(),
-          groups_for_docs: keyword((keyword() -> boolean)),
-          groups_for_modules: keyword(),
+          groups_for_extras: [{binary(), term()}],
+          groups_for_docs: [{binary(), (keyword() -> boolean)}],
+          groups_for_modules: [{binary(), term()}],
           homepage_url: nil | String.t(),
           language: String.t(),
           logo: nil | Path.t(),
@@ -96,7 +99,6 @@ defmodule ExDoc.Config do
   @spec build(String.t(), String.t(), Keyword.t()) :: ExDoc.Config.t()
   def build(project, vsn, options) do
     {output, options} = Keyword.pop(options, :output, "./doc")
-    {groups_for_modules, options} = Keyword.pop(options, :groups_for_modules, [])
     {nest_modules_by_prefix, options} = Keyword.pop(options, :nest_modules_by_prefix, [])
     {proglang, options} = Keyword.pop(options, :proglang, :elixir)
     {filter_modules, options} = Keyword.pop(options, :filter_modules, &filter_modules/2)
@@ -109,6 +111,10 @@ defmodule ExDoc.Config do
         options
       end
 
+    {groups_for_docs, options} = Keyword.pop(options, :groups_for_docs, [])
+    {groups_for_extras, options} = Keyword.pop(options, :groups_for_extras, [])
+    {groups_for_modules, options} = Keyword.pop(options, :groups_for_modules, [])
+
     {skip_undefined_reference_warnings_on, options} =
       Keyword.pop(
         options,
@@ -126,7 +132,13 @@ defmodule ExDoc.Config do
 
     preconfig = %__MODULE__{
       filter_modules: normalize_filter_modules(filter_modules),
-      groups_for_modules: normalize_groups_for_modules(groups_for_modules),
+      groups_for_docs: normalize_groups(groups_for_docs),
+      groups_for_extras: normalize_groups(groups_for_extras),
+      groups_for_modules:
+        normalize_groups(
+          # TODO: The default module groups must be returned by the language
+          groups_for_modules ++ [Deprecated: &deprecated?/1, Exceptions: &exception?/1]
+        ),
       homepage_url: options[:homepage_url],
       main: options[:main],
       nest_modules_by_prefix: normalize_nest_modules_by_prefix(nest_modules_by_prefix),
@@ -159,12 +171,8 @@ defmodule ExDoc.Config do
     raise ArgumentError, "#{inspect(proglang)} is not supported"
   end
 
-  # TODO: The default module groups must be returned by the language
-  defp normalize_groups_for_modules(groups_for_modules) do
-    default_groups = [Deprecated: &deprecated?/1, Exceptions: &exception?/1]
-
-    groups_for_modules ++
-      Enum.reject(default_groups, fn {k, _} -> Keyword.has_key?(groups_for_modules, k) end)
+  defp normalize_groups(groups) do
+    for {k, v} <- groups, do: {to_string(k), v}
   end
 
   defp deprecated?(metadata), do: metadata[:deprecated] != nil
diff --git a/lib/ex_doc/formatter/html.ex b/lib/ex_doc/formatter/html.ex
index 1bbaacad2..2e7a32e61 100644
--- a/lib/ex_doc/formatter/html.ex
+++ b/lib/ex_doc/formatter/html.ex
@@ -383,7 +383,7 @@ defmodule ExDoc.Formatter.HTML do
       if ids_count[extra.id] > 1, do: {disambiguate_id(extra, idx), idx + 1}, else: {extra, idx}
     end)
     |> elem(0)
-    |> Enum.sort_by(fn extra -> GroupMatcher.group_index(groups, extra.group) end)
+    |> Enum.sort_by(fn extra -> GroupMatcher.index(groups, extra.group) end)
   end
 
   def generate_redirects(config, ext) do
diff --git a/lib/ex_doc/formatter/html/templates.ex b/lib/ex_doc/formatter/html/templates.ex
index d8b118385..fbd96c162 100644
--- a/lib/ex_doc/formatter/html/templates.ex
+++ b/lib/ex_doc/formatter/html/templates.ex
@@ -203,13 +203,12 @@ defmodule ExDoc.Formatter.HTML.Templates do
   end
 
   def module_summary(module_node) do
-    entries = docs_groups(module_node.docs_groups, module_node.docs ++ module_node.typespecs)
-
-    Enum.reject(entries, fn {_type, nodes} -> nodes == [] end)
-  end
-
-  defp docs_groups(groups, docs) do
-    for group <- groups, do: {group, Enum.filter(docs, &(&1.group == group))}
+    # TODO: Maybe it should be moved to retriever and it already returned grouped metadata
+    ExDoc.GroupMatcher.group_by(
+      module_node.docs_groups,
+      module_node.docs ++ module_node.typespecs,
+      & &1.group
+    )
   end
 
   defp logo_path(%{logo: nil}), do: nil
diff --git a/lib/ex_doc/group_matcher.ex b/lib/ex_doc/group_matcher.ex
index 499fc02f5..ae021e42c 100644
--- a/lib/ex_doc/group_matcher.ex
+++ b/lib/ex_doc/group_matcher.ex
@@ -8,22 +8,38 @@ defmodule ExDoc.GroupMatcher do
   @doc """
   Finds the index of a given group.
   """
-  def group_index(groups, group) do
+  def index(groups, group) do
     Enum.find_index(groups, fn {k, _v} -> k == group end) || -1
   end
 
+  @doc """
+  Group the following entries and while preserving the order in `groups`.
+  """
+  def group_by(groups, entries, by) do
+    entries = Enum.group_by(entries, by)
+
+    {groups, leftovers} =
+      Enum.flat_map_reduce(groups, entries, fn group, grouped_nodes ->
+        case Map.pop(grouped_nodes, group, []) do
+          {[], grouped_nodes} -> {[], grouped_nodes}
+          {entries, grouped_nodes} -> {[{group, entries}], grouped_nodes}
+        end
+      end)
+
+    groups ++ Enum.sort(leftovers)
+  end
+
   @doc """
   Finds a matching group for the given function.
   """
-  @spec match_function(group_patterns, map) :: atom() | nil
-  def match_function(group_patterns, metadata) do
-    match_group_patterns(group_patterns, fn pattern -> pattern.(metadata) end)
+  def match_doc(group_patterns, callback, default, metadata) do
+    match_group_patterns(group_patterns, fn pattern -> pattern.(metadata) end) ||
+      callback.(metadata) || default
   end
 
   @doc """
   Finds a matching group for the given module name, id, and metadata.
   """
-  @spec match_module(group_patterns, module, binary, map) :: atom() | nil
   def match_module(group_patterns, module, id, metadata) do
     match_group_patterns(group_patterns, fn pattern ->
       case pattern do
@@ -38,7 +54,6 @@ defmodule ExDoc.GroupMatcher do
   @doc """
   Finds a matching group for the given extra filename
   """
-  @spec match_extra(group_patterns, binary) :: atom() | nil
   def match_extra(group_patterns, filename) do
     match_group_patterns(group_patterns, fn pattern ->
       case pattern do
diff --git a/lib/ex_doc/language.ex b/lib/ex_doc/language.ex
index eb84bee5f..0888052c8 100644
--- a/lib/ex_doc/language.ex
+++ b/lib/ex_doc/language.ex
@@ -49,10 +49,10 @@ defmodule ExDoc.Language do
   @doc """
   Returns a map with module information.
   """
-  @callback module_data(module(), tuple(), ExDoc.Config.t()) :: module_data() | :skip
+  @callback module_data(module(), tuple(), ExDoc.Config.t()) :: module_data() | false
 
   @doc """
-  Returns a map with function information or an atom `:skip`.
+  Returns a map with function information or `false`.
 
   The map has the following keys:
 
@@ -78,7 +78,7 @@ defmodule ExDoc.Language do
                 doc_fallback: (... -> ExDoc.DocAST.t()) | nil,
                 extra_annotations: [String.t()]
               }
-              | :skip
+              | false
 
   @doc """
   Returns a map with callback information.
diff --git a/lib/ex_doc/language/elixir.ex b/lib/ex_doc/language/elixir.ex
index 0d79f6dab..c596adb03 100644
--- a/lib/ex_doc/language/elixir.ex
+++ b/lib/ex_doc/language/elixir.ex
@@ -8,7 +8,7 @@ defmodule ExDoc.Language.Elixir do
 
   @impl true
   @spec module_data(atom, any, any) ::
-          :skip
+          false
           | %{
               callback_types: [:callback, ...],
               docs: any,
@@ -34,7 +34,7 @@ defmodule ExDoc.Language.Elixir do
 
     cond do
       skip ->
-        :skip
+        false
 
       abst_code = Source.get_abstract_code(module) ->
         title = module_title(module, type)
@@ -73,7 +73,7 @@ defmodule ExDoc.Language.Elixir do
           []
         )
 
-        :skip
+        false
     end
   end
 
@@ -84,7 +84,7 @@ defmodule ExDoc.Language.Elixir do
     if doc?(entry, module_data.type) do
       function_data(kind, name, arity, anno, metadata, module_data)
     else
-      :skip
+      false
     end
   end
 
diff --git a/lib/ex_doc/language/erlang.ex b/lib/ex_doc/language/erlang.ex
index 946858711..f28878b86 100644
--- a/lib/ex_doc/language/erlang.ex
+++ b/lib/ex_doc/language/erlang.ex
@@ -8,7 +8,7 @@ defmodule ExDoc.Language.Erlang do
 
   @impl true
   @spec module_data(atom, any, any) ::
-          :skip
+          false
           | %{
               callback_types: [:callback, ...],
               docs: any,
@@ -54,7 +54,7 @@ defmodule ExDoc.Language.Erlang do
       }
     else
       ExDoc.Utils.warn("skipping docs for module #{inspect(module)}, reason: :no_debug_info", [])
-      :skip
+      false
     end
   end
 
@@ -68,7 +68,7 @@ defmodule ExDoc.Language.Erlang do
          function_exported?(module_data.module, name, arity) do
       function_data(name, arity, doc_content, module_data, metadata)
     else
-      :skip
+      false
     end
   end
 
diff --git a/lib/ex_doc/retriever.ex b/lib/ex_doc/retriever.ex
index 76225a7b2..2649c7794 100644
--- a/lib/ex_doc/retriever.ex
+++ b/lib/ex_doc/retriever.ex
@@ -69,7 +69,7 @@ defmodule ExDoc.Retriever do
 
   defp sort_modules(modules, config) when is_list(modules) do
     Enum.sort_by(modules, fn module ->
-      {GroupMatcher.group_index(config.groups_for_modules, module.group), module.nested_context,
+      {GroupMatcher.index(config.groups_for_modules, module.group), module.nested_context,
        module.nested_title, module.id}
     end)
   end
@@ -135,24 +135,18 @@ defmodule ExDoc.Retriever do
     {doc_line, doc_file, format, source_doc, doc, metadata} = get_module_docs(module_data, source)
 
     # TODO: The default function groups must be returned by the language
-    groups_for_docs =
-      config.groups_for_docs ++
-        [
-          Types: &(&1[:kind] in [:type, :opaque, :nominal]),
-          Callbacks: &(&1[:kind] in [:callback, :macrocallback]),
-          Functions: fn _ -> true end
-        ]
-
+    default_group = config.default_group_for_doc
+    groups_for_docs = config.groups_for_docs
     annotations_for_docs = config.annotations_for_docs
 
-    docs_groups = Enum.map(groups_for_docs, &elem(&1, 0)) |> Enum.uniq()
-    function_docs = get_docs(module_data, source, groups_for_docs, annotations_for_docs)
+    docs_groups =
+      Enum.uniq(Enum.map(groups_for_docs, &elem(&1, 0)) ++ ~w(Types Callbacks Functions))
 
     docs =
-      function_docs ++
-        get_callbacks(module_data, source, groups_for_docs, annotations_for_docs)
+      get_docs(module_data, source, default_group, groups_for_docs, annotations_for_docs) ++
+        get_callbacks(module_data, source, default_group, groups_for_docs, annotations_for_docs)
 
-    types = get_types(module_data, source, groups_for_docs, annotations_for_docs)
+    types = get_types(module_data, source, default_group, groups_for_docs, annotations_for_docs)
 
     metadata = Map.put(metadata, :kind, module_data.type)
     group = GroupMatcher.match_module(config.groups_for_modules, module, module_data.id, metadata)
@@ -202,42 +196,37 @@ defmodule ExDoc.Retriever do
 
   ## Function helpers
 
-  defp get_docs(module_data, source, groups_for_docs, annotations_for_docs) do
-    {:docs_v1, _, _, _, _, _, doc_elements} = module_data.docs
+  defp get_docs(module_data, source, default_group, groups_for_docs, annotations_for_docs) do
+    {:docs_v1, _, _, _, _, _, docs} = module_data.docs
 
     nodes =
-      Enum.flat_map(doc_elements, fn doc_element ->
-        case module_data.language.function_data(doc_element, module_data) do
-          :skip ->
-            []
-
-          function_data ->
-            [
-              get_function(
-                doc_element,
-                function_data,
-                source,
-                module_data,
-                groups_for_docs,
-                annotations_for_docs
-              )
-            ]
-        end
-      end)
+      for doc <- docs,
+          function_data = module_data.language.function_data(doc, module_data) do
+        get_function(
+          doc,
+          function_data,
+          module_data,
+          source,
+          default_group,
+          groups_for_docs,
+          annotations_for_docs
+        )
+      end
 
     filter_defaults(nodes)
   end
 
   defp get_function(
-         doc_element,
+         doc,
          function_data,
-         source,
          module_data,
+         source,
+         default_group,
          groups_for_docs,
          annotations_for_docs
        ) do
     {:docs_v1, _, _, content_type, _, module_metadata, _} = module_data.docs
-    {{type, name, arity}, anno, signature, source_doc, metadata} = doc_element
+    {{type, name, arity}, anno, signature, source_doc, metadata} = doc
     doc_file = anno_file(anno, source)
     doc_line = anno_line(anno)
 
@@ -259,7 +248,7 @@ defmodule ExDoc.Retriever do
       (source_doc && doc_ast(content_type, source_doc, file: doc_file, line: doc_line + 1)) ||
         function_data.doc_fallback.()
 
-    group = GroupMatcher.match_function(groups_for_docs, metadata)
+    group = GroupMatcher.match_doc(groups_for_docs, default_group, "Functions", metadata)
 
     %ExDoc.FunctionNode{
       id: nil_or_name(name, arity),
@@ -303,23 +292,31 @@ defmodule ExDoc.Retriever do
   defp get_callbacks(
          %{type: :behaviour} = module_data,
          source,
+         default_group,
          groups_for_docs,
          annotations_for_docs
        ) do
     {:docs_v1, _, _, _, _, _, docs} = module_data.docs
 
     for {{kind, _, _}, _, _, _, _} = doc <- docs, kind in module_data.callback_types do
-      get_callback(doc, source, groups_for_docs, module_data, annotations_for_docs)
+      get_callback(doc, module_data, source, default_group, groups_for_docs, annotations_for_docs)
     end
   end
 
-  defp get_callbacks(_, _, _, _), do: []
+  defp get_callbacks(_, _, _, _, _), do: []
 
-  defp get_callback(callback, source, groups_for_docs, module_data, annotations_for_docs) do
-    callback_data = module_data.language.callback_data(callback, module_data)
+  defp get_callback(
+         doc,
+         module_data,
+         source,
+         default_group,
+         groups_for_docs,
+         annotations_for_docs
+       ) do
+    callback_data = module_data.language.callback_data(doc, module_data)
 
     {:docs_v1, _, _, content_type, _, module_metadata, _} = module_data.docs
-    {{kind, name, arity}, anno, _signature, source_doc, metadata} = callback
+    {{kind, name, arity}, anno, _signature, source_doc, metadata} = doc
     doc_file = anno_file(anno, source)
     doc_line = anno_line(anno)
 
@@ -342,11 +339,7 @@ defmodule ExDoc.Retriever do
       doc_ast(content_type, source_doc, file: doc_file, line: doc_line + 1) ||
         doc_fallback(callback_data)
 
-    group =
-      GroupMatcher.match_function(
-        groups_for_docs,
-        metadata
-      )
+    group = GroupMatcher.match_doc(groups_for_docs, default_group, "Callbacks", metadata)
 
     %ExDoc.FunctionNode{
       id: "c:" <> nil_or_name(name, arity),
@@ -368,21 +361,21 @@ defmodule ExDoc.Retriever do
 
   ## Typespecs
 
-  defp get_types(module_data, source, groups_for_docs, annotations_for_docs) do
+  defp get_types(module_data, source, default_group, groups_for_docs, annotations_for_docs) do
     {:docs_v1, _, _, _, _, _, docs} = module_data.docs
 
     for {{:type, _, _}, _, _, content, _} = doc <- docs, content != :hidden do
-      get_type(doc, source, groups_for_docs, module_data, annotations_for_docs)
+      get_type(doc, module_data, source, default_group, groups_for_docs, annotations_for_docs)
     end
   end
 
-  defp get_type(type_entry, source, groups_for_docs, module_data, annotations_for_docs) do
+  defp get_type(doc, module_data, source, default_group, groups_for_docs, annotations_for_docs) do
     {:docs_v1, _, _, content_type, _, module_metadata, _} = module_data.docs
-    {{kind, name, arity}, anno, _signature, source_doc, metadata} = type_entry
+    {{kind, name, arity}, anno, _signature, source_doc, metadata} = doc
     doc_file = anno_file(anno, source)
     doc_line = anno_line(anno)
 
-    type_data = module_data.language.type_data(type_entry, module_data)
+    type_data = module_data.language.type_data(doc, module_data)
 
     metadata =
       Map.merge(
@@ -403,11 +396,7 @@ defmodule ExDoc.Retriever do
       doc_ast(content_type, source_doc, file: doc_file, line: doc_line + 1) ||
         doc_fallback(type_data)
 
-    group =
-      GroupMatcher.match_function(
-        groups_for_docs,
-        metadata
-      )
+    group = GroupMatcher.match_doc(groups_for_docs, default_group, "Types", metadata)
 
     %ExDoc.TypeNode{
       id: "t:" <> nil_or_name(name, arity),
diff --git a/lib/mix/tasks/docs.ex b/lib/mix/tasks/docs.ex
index 3fb6b44ee..1c8d09d54 100644
--- a/lib/mix/tasks/docs.ex
+++ b/lib/mix/tasks/docs.ex
@@ -124,7 +124,8 @@ defmodule Mix.Tasks.Docs do
 
     * `:formatters` - Formatter to use; default: ["html", "epub"], options: "html", "epub".
 
-    * `:groups_for_extras`, `:groups_for_modules`, `:groups_for_docs` - See the "Groups" section
+    * `:groups_for_extras`, `:groups_for_modules`, `:groups_for_docs`, and `:default_group_for_doc` -
+      See the "Groups" section
 
     * `:ignore_apps` - Apps to be ignored when generating documentation in an umbrella project.
       Receives a list of atoms. Example: `[:first_app, :second_app]`.
@@ -245,15 +246,41 @@ defmodule Mix.Tasks.Docs do
 
   A regex or the string name of the module is also supported.
 
-  ### Grouping functions and callbacks
+  ### Grouping functions, types, and callbacks
 
-  Functions and callbacks inside a module can also be organized in groups.
-  This is done via the `:groups_for_docs` configuration which is a
-  keyword list of group titles and filtering functions that receive the
-  documentation metadata of functions as argument. The metadata received will also
-  contain `:module`, `:name`, `:arity` and `:kind` to help identify which entity is
-  currently being processed.
+  Types, functions, and callbacks inside a module can also be organized in groups.
+  By default, ExDoc respects the `:group` metadata field:
 
+      @doc group: "Queries"
+      def get_by(schema, fields)
+
+  The function above will be automatically listed under the "Queries" section in
+  the sidebar. The benefit of using `:group` is that it can also be used by tools
+  such as IEx during autocompletion. These groups are then ordered alphabetically
+  in the sidebar.
+
+  It is also possible to tell ExDoc to either enrich the group metadata or lookup a
+  different field via the `:default_group_for_doc` configuration. The default is:
+
+      default_group_for_doc: fn metadata -> metadata[:group] end
+
+  The `metadata` received contains all of the documentation metadata, such as `:group`,
+  but also `:module`, `:name`, `:arity` and `:kind` to help identify which entity is
+  currently being processed. For example, projects like Nx have a custom function that
+  converts "Queries" into "Function: Queries":
+
+      default_group_for_doc: fn metadata ->
+        if group = metadata[:group] do
+          "Functions: #{group}"
+        end
+      end
+
+  Whenever using the `:group` key, the groups will be ordered alphabetically.
+  If you also want control over the group order, you can also use the `:groups_for_docs`
+  which works similarly as the one for modules/extra pages.
+
+  `:groups_for_docs` is a keyword list of group titles and filtering functions
+  that receive the documentation metadata and must return a boolean.
   For example, imagine that you have an API client library with a large surface
   area for all the API endpoints you need to support. It would be helpful to
   group the functions with similar responsibilities together. In this case in
@@ -278,10 +305,11 @@ defmodule Mix.Tasks.Docs do
         Admin: & &1[:permission] in [:grant, :write]
       ]
 
-  A function can belong to a single group only. If multiple group filters match,
-  the first will take precedence. Functions and callbacks that don't have a
-  custom group will be listed under the default "Functions" and "Callbacks"
-  group respectively.
+  A function can belong to a single group only. The first group that matches
+  will be the one used. In case no group is found in `:groups_for_docs`,
+  the `:default_group_for_doc` callback is invoked. If it returns nil, it
+  then falls back to the appropriate "Functions", "Types" or "Callbacks"
+  section respectively.
 
   ## Meta-tags configuration
 
diff --git a/test/ex_doc/group_matcher_test.exs b/test/ex_doc/group_matcher_test.exs
index eafb2b0f3..9f5832570 100644
--- a/test/ex_doc/group_matcher_test.exs
+++ b/test/ex_doc/group_matcher_test.exs
@@ -2,8 +2,18 @@ defmodule ExDoc.GroupMatcherTest do
   use ExUnit.Case, async: true
   import ExDoc.GroupMatcher
 
+  describe "group_by" do
+    test "group by given data with leftovers" do
+      assert group_by([1, 3, 5], [%{key: 1}, %{key: 3}, %{key: 2}], & &1.key) == [
+               {1, [%{key: 1}]},
+               {3, [%{key: 3}]},
+               {2, [%{key: 2}]}
+             ]
+    end
+  end
+
   describe "module matching" do
-    test "match modules by their atom names" do
+    test "by atom names" do
       patterns = [
         Group: [MyApp.SomeModule, :lists]
       ]
@@ -22,7 +32,7 @@ defmodule ExDoc.GroupMatcherTest do
                nil
     end
 
-    test "match modules by their string names" do
+    test "by string names" do
       patterns = [
         Group: ["MyApp.SomeModule", ":lists"]
       ]
@@ -36,7 +46,7 @@ defmodule ExDoc.GroupMatcherTest do
                nil
     end
 
-    test "match modules by regular expressions" do
+    test "by regular expressions" do
       patterns = [
         Group: ~r/MyApp\..?/
       ]
@@ -53,7 +63,7 @@ defmodule ExDoc.GroupMatcherTest do
   end
 
   describe "extras matching" do
-    test "it can match extra files by their string names" do
+    test "by string names" do
       patterns = [
         Group: ["docs/handling/testing.md"]
       ]
@@ -62,7 +72,7 @@ defmodule ExDoc.GroupMatcherTest do
       assert match_extra(patterns, "docs/handling/setup.md") == nil
     end
 
-    test "it can match extra files by regular expressions" do
+    test "by regular expressions" do
       patterns = [
         Group: ~r/docs\/handling?/
       ]
diff --git a/test/ex_doc/retriever/elixir_test.exs b/test/ex_doc/retriever/elixir_test.exs
index ea7008594..34b508273 100644
--- a/test/ex_doc/retriever/elixir_test.exs
+++ b/test/ex_doc/retriever/elixir_test.exs
@@ -48,7 +48,7 @@ defmodule ExDoc.Retriever.ElixirTest do
                defaults: [],
                deprecated: nil,
                doc_line: 5,
-               group: :Functions,
+               group: "Functions",
                id: "function/0",
                name: :function,
                rendered_doc: nil,
@@ -136,7 +136,7 @@ defmodule ExDoc.Retriever.ElixirTest do
       assert callback1.type == :callback
       assert callback1.annotations == []
       assert callback1.doc_line == 2
-      assert callback1.group == :Callbacks
+      assert callback1.group == "Callbacks"
       assert Path.basename(callback1.source_url) == "nofile:3"
       assert DocAST.to_string(callback1.doc) == "<p>callback1/0 docs.</p>"
       assert Macro.to_string(callback1.specs) == "[callback1() :: :ok]"
@@ -146,7 +146,7 @@ defmodule ExDoc.Retriever.ElixirTest do
       assert optional_callback1.type == :callback
       assert optional_callback1.annotations == ["optional"]
       assert optional_callback1.doc_line == 5
-      assert optional_callback1.group == :Callbacks
+      assert optional_callback1.group == "Callbacks"
       assert Path.basename(optional_callback1.source_url) == "nofile:5"
       refute optional_callback1.doc
       assert Macro.to_string(optional_callback1.specs) == "[optional_callback1() :: :ok]"
@@ -156,7 +156,7 @@ defmodule ExDoc.Retriever.ElixirTest do
       assert macrocallback1.type == :macrocallback
       assert macrocallback1.annotations == []
       assert macrocallback1.doc_line == 9
-      assert macrocallback1.group == :Callbacks
+      assert macrocallback1.group == "Callbacks"
       assert Path.basename(macrocallback1.source_url) == "nofile:9"
       refute macrocallback1.doc
       assert Macro.to_string(macrocallback1.specs) == "[macrocallback1() :: :ok]"
@@ -207,7 +207,7 @@ defmodule ExDoc.Retriever.ElixirTest do
       assert type1.id == "t:type1/0"
       assert type1.signature == "type1()"
       assert type1.type == :type
-      assert type1.group == :Types
+      assert type1.group == "Types"
       assert type1.annotations == []
       assert type1.doc_line == 2
       assert DocAST.to_string(type1.doc) == "<p>type1/0 docs.</p>"
@@ -216,7 +216,7 @@ defmodule ExDoc.Retriever.ElixirTest do
       assert opaque1.id == "t:opaque1/0"
       assert opaque1.signature == "opaque1()"
       assert opaque1.type == :opaque
-      assert opaque1.group == :Types
+      assert opaque1.group == "Types"
       assert opaque1.doc_line == 5
       assert opaque1.doc |> DocAST.to_string() == ~s|<p>opaque1/0 docs.</p>|
       assert opaque1.spec |> Macro.to_string() == "opaque1()"
diff --git a/test/ex_doc/retriever/erlang_test.exs b/test/ex_doc/retriever/erlang_test.exs
index 9220ddc6d..2b8d31496 100644
--- a/test/ex_doc/retriever/erlang_test.exs
+++ b/test/ex_doc/retriever/erlang_test.exs
@@ -55,7 +55,7 @@ defmodule ExDoc.Retriever.ErlangTest do
         moduledoc_line: 2,
         moduledoc_file: moduledoc_file,
         docs: [equiv_function2, function1, function2],
-        docs_groups: [:Types, :Callbacks, :Functions],
+        docs_groups: ["Types", "Callbacks", "Functions"],
         group: nil,
         id: "mod",
         language: ExDoc.Language.Erlang,
@@ -80,7 +80,7 @@ defmodule ExDoc.Retriever.ErlangTest do
         deprecated: nil,
         doc_line: 5,
         doc_file: _,
-        group: :Functions,
+        group: "Functions",
         id: "function1/0",
         name: :function1,
         rendered_doc: nil,
@@ -157,7 +157,7 @@ defmodule ExDoc.Retriever.ErlangTest do
                moduledoc_line: 6,
                moduledoc_file: moduledoc_file,
                docs: [callback, function],
-               docs_groups: [:Types, :Callbacks, :Functions],
+               docs_groups: ["Types", "Callbacks", "Functions"],
                group: nil,
                id: "mod",
                language: ExDoc.Language.Erlang,
@@ -182,7 +182,7 @@ defmodule ExDoc.Retriever.ErlangTest do
                deprecated: nil,
                doc_line: 2,
                doc_file: _,
-               group: :Functions,
+               group: "Functions",
                id: "function/0",
                name: :function,
                rendered_doc: nil,
@@ -251,7 +251,7 @@ defmodule ExDoc.Retriever.ErlangTest do
       assert callback1.id == "c:callback1/0"
       assert callback1.type == :callback
       assert callback1.annotations == []
-      assert callback1.group == :Callbacks
+      assert callback1.group == "Callbacks"
       assert DocAST.to_string(callback1.doc) =~ "callback1/0 docs."
       assert Path.basename(callback1.source_url) == "mod.erl:4"
 
@@ -261,7 +261,7 @@ defmodule ExDoc.Retriever.ErlangTest do
       assert equiv_callback1.id == "c:equiv_callback1/0"
       assert equiv_callback1.type == :callback
       assert equiv_callback1.annotations == []
-      assert equiv_callback1.group == :Callbacks
+      assert equiv_callback1.group == "Callbacks"
 
       assert DocAST.to_string(equiv_callback1.doc) =~
                ~r'Equivalent to <a href="`c:callback1/0`"><code[^>]+>callback1().*\.'
@@ -270,7 +270,7 @@ defmodule ExDoc.Retriever.ErlangTest do
 
       assert optional_callback1.id == "c:optional_callback1/0"
       assert optional_callback1.type == :callback
-      assert optional_callback1.group == :Callbacks
+      assert optional_callback1.group == "Callbacks"
       assert optional_callback1.annotations == ["optional"]
     end
 
@@ -298,7 +298,7 @@ defmodule ExDoc.Retriever.ErlangTest do
 
       assert opaque1.id == "t:opaque1/0"
       assert opaque1.type == :opaque
-      assert opaque1.group == :Types
+      assert opaque1.group == "Types"
       assert opaque1.signature == "opaque1()"
       assert opaque1.doc |> DocAST.to_string() =~ "opaque1/0 docs."
 
@@ -307,7 +307,7 @@ defmodule ExDoc.Retriever.ErlangTest do
 
       assert nominal1.id == "t:nominal1/0"
       assert nominal1.type == @nominal_type
-      assert nominal1.group == :Types
+      assert nominal1.group == "Types"
       assert nominal1.signature == "nominal1()"
       assert nominal1.doc |> DocAST.to_string() =~ "nominal1/0 docs."
 
@@ -316,7 +316,7 @@ defmodule ExDoc.Retriever.ErlangTest do
 
       assert type1.id == "t:type1/0"
       assert type1.type == :type
-      assert type1.group == :Types
+      assert type1.group == "Types"
       assert type1.signature == "type1()"
       assert type1.doc |> DocAST.to_string() =~ "type1/0 docs."
 
@@ -325,7 +325,7 @@ defmodule ExDoc.Retriever.ErlangTest do
 
       assert equiv_type1.id == "t:equiv_type1/0"
       assert equiv_type1.type == :type
-      assert equiv_type1.group == :Types
+      assert equiv_type1.group == "Types"
       assert equiv_type1.signature == "equiv_type1()"
       assert equiv_type1.doc |> DocAST.to_string() =~ ~r'Equivalent to .*t:type1/1.*\.'
     end
@@ -401,7 +401,7 @@ defmodule ExDoc.Retriever.ErlangTest do
         deprecated: nil,
         moduledoc_line: _,
         docs: [function1, function2],
-        docs_groups: [:Types, :Callbacks, :Functions],
+        docs_groups: ["Types", "Callbacks", "Functions"],
         group: nil,
         id: "mod",
         language: ExDoc.Language.Erlang,
@@ -425,7 +425,7 @@ defmodule ExDoc.Retriever.ErlangTest do
         deprecated: nil,
         doc_line: _,
         doc_file: _,
-        group: :Functions,
+        group: "Functions",
         id: "function1/0",
         name: :function1,
         rendered_doc: nil,
@@ -523,7 +523,7 @@ defmodule ExDoc.Retriever.ErlangTest do
 
       assert nominal1.id == "t:nominal1/0"
       assert nominal1.type == @nominal_type
-      assert nominal1.group == :Types
+      assert nominal1.group == "Types"
       assert nominal1.signature == "nominal1/0"
       assert nominal1.doc |> DocAST.to_string() =~ "nominal1/0 docs."
 
diff --git a/test/ex_doc/retriever_test.exs b/test/ex_doc/retriever_test.exs
index 471c75fb0..7708d8889 100644
--- a/test/ex_doc/retriever_test.exs
+++ b/test/ex_doc/retriever_test.exs
@@ -50,15 +50,15 @@ defmodule ExDoc.RetrieverTest do
 
       config = %ExDoc.Config{
         groups_for_modules: [
-          "Group 1": [Foo, Bar],
-          "Group 2": [Baz]
+          {"Group 1", [Foo, Bar]},
+          {"Group 2", [Baz]}
         ]
       }
 
       {[qux, bar, foo, baz], []} = Retriever.docs_from_modules([Foo, Bar, Baz, Qux], config)
-      assert %{module: Foo, group: :"Group 1"} = foo
-      assert %{module: Bar, group: :"Group 1"} = bar
-      assert %{module: Baz, group: :"Group 2"} = baz
+      assert %{module: Foo, group: "Group 1"} = foo
+      assert %{module: Bar, group: "Group 1"} = bar
+      assert %{module: Baz, group: "Group 2"} = baz
       assert %{module: Qux, group: nil} = qux
     end
 
@@ -78,17 +78,63 @@ defmodule ExDoc.RetrieverTest do
 
       config = %ExDoc.Config{
         groups_for_docs: [
-          "Group 1": &(&1.group == 1),
-          "Group 2": &(&1.group == 2)
+          {"Group 1", &(&1.group == 1)},
+          {"Group 2", &(&1.group == 2)}
         ]
       }
 
       {[mod], []} = Retriever.docs_from_modules([A], config)
       [bar, baz, foo] = mod.docs
 
-      assert %{id: "foo/0", group: :"Group 1"} = foo
-      assert %{id: "bar/0", group: :"Group 1"} = bar
-      assert %{id: "baz/0", group: :"Group 2"} = baz
+      assert %{id: "foo/0", group: "Group 1"} = foo
+      assert %{id: "bar/0", group: "Group 1"} = bar
+      assert %{id: "baz/0", group: "Group 2"} = baz
+    end
+
+    test "function groups use :group metadata", c do
+      elixirc(c, ~S"""
+      defmodule A do
+        @doc group: "a"
+        @callback foo() :: :ok
+
+        @doc group: "b"
+        def bar(), do: :ok
+
+        @doc group: "c"
+        def baz(), do: :ok
+      end
+      """)
+
+      config = %ExDoc.Config{}
+      {[mod], []} = Retriever.docs_from_modules([A], config)
+      [bar, baz, foo] = mod.docs
+
+      assert %{id: "c:foo/0", group: "a"} = foo
+      assert %{id: "bar/0", group: "b"} = bar
+      assert %{id: "baz/0", group: "c"} = baz
+    end
+
+    test "function groups use default_group_for_doc", c do
+      elixirc(c, ~S"""
+      defmodule A do
+        @doc semi_group: "a"
+        @callback foo() :: :ok
+
+        @doc semi_group: "b"
+        def bar(), do: :ok
+
+        @doc semi_group: "c"
+        def baz(), do: :ok
+      end
+      """)
+
+      config = %ExDoc.Config{default_group_for_doc: & &1[:semi_group]}
+      {[mod], []} = Retriever.docs_from_modules([A], config)
+      [bar, baz, foo] = mod.docs
+
+      assert %{id: "c:foo/0", group: "a"} = foo
+      assert %{id: "bar/0", group: "b"} = bar
+      assert %{id: "baz/0", group: "c"} = baz
     end
 
     test "function annotations", c do