Update exception terminology to clarify types of exceptions

Author: Bahaaio

concepts/exceptions/about.md

@@ -8,11 +8,10 @@ An exception is an event that occurs during the execution of a program that disr
 Exceptions are raised explicitly in Java, and the act of raising an exception is called _throwing an exception_.
 The act of handling an exception is called _catching an exception_.
 
-Java distinguishes three types of exceptions:
+Java distinguishes two types of exceptions:
 
 1. Checked exceptions
 2. Unchecked exceptions
-3. Errors
 
 ### Checked exceptions
 
@@ -21,7 +20,7 @@ An example of a checked exception is the `FileNotFoundException` which occurs wh
 
 This type of exception is checked at compile-time: methods that throw checked exceptions should specify this in their method signature, and code calling a method that might throw a checked exception is required to handle it or the code will not compile.
 
-All exceptions in Java that do not inherit from `RuntimeException` or `Error` are considered checked exceptions.
+All exceptions in Java that do not inherit from `RuntimeException` are checked exceptions.
 
 ### Unchecked exceptions
 
@@ -30,17 +29,15 @@ An example of an unchecked exception is the `NullPointerException` which occurs
 
 This type of exception is not checked at compile-time: methods that throw unchecked exceptions are not required to specify this in their method signature, and code calling a method that might throw an unchecked exception is not required to handle it.
 
-All exceptions in Java that inherit from `RuntimeException` are considered unchecked exceptions.
+All exceptions in Java that inherit from `RuntimeException` are unchecked exceptions.
 
-### Errors
+## Errors
 
-_Errors_ are exceptional conditions that are external to an application.
-An example of an error is the `OutOfMemoryError` which occurs when an application is trying to use more memory than is available on the system.
+Java also has a separate category called _Errors_ which are serious problems that are external to an application. An example of an error is the `OutOfMemoryError` which occurs when an application is trying to use more memory than is available on the system.
 
-Like unchecked exceptions, errors are not checked at compile-time.
-They are not usually thrown from application code.
+Like unchecked exceptions, errors are not checked at compile-time and are not usually thrown from application code. Unlike exceptions, Errors represent serious system-level problems that applications should generally not attempt to catch or handle.
 
-All exceptions in Java that inherit from `Error` are considered errors.
+All errors in Java inherit from the `Error` class.
 
 ## Throwing exceptions
 

concepts/exceptions/introduction.md

@@ -8,11 +8,10 @@ An exception is an event that occurs during the execution of a program that disr
 Exceptions are raised explicitly in Java, and the act of raising an exception is called _throwing an exception_.
 The act of handling an exception is called _catching an exception_.
 
-Java distinguishes three types of exceptions:
+Java distinguishes two types of exceptions:
 
 1. Checked exceptions
 2. Unchecked exceptions
-3. Errors
 
 ### Checked exceptions
 
@@ -21,7 +20,7 @@ An example of a checked exception is the `FileNotFoundException` which occurs wh
 
 This type of exception is checked at compile-time: methods that throw checked exceptions should specify this in their method signature, and code calling a method that might throw a checked exception is required to handle it or the code will not compile.
 
-All exceptions in Java that do not inherit from `RuntimeException` or `Error` are considered checked exceptions.
+All exceptions in Java that do not inherit from `RuntimeException` are checked exceptions.
 
 ### Unchecked exceptions
 
@@ -30,17 +29,15 @@ An example of an unchecked exception is the `NullPointerException` which occurs
 
 This type of exception is not checked at compile-time: methods that throw unchecked exceptions are not required to specify this in their method signature, and code calling a method that might throw an unchecked exception is not required to handle it.
 
-All exceptions in Java that inherit from `RuntimeException` are considered unchecked exceptions.
+All exceptions in Java that inherit from `RuntimeException` are unchecked exceptions.
 
-### Errors
+## Errors
 
-_Errors_ are exceptional conditions that are external to an application.
-An example of an error is the `OutOfMemoryError` which occurs when an application is trying to use more memory than is available on the system.
+Java also has a separate category called _Errors_ which are serious problems that are external to an application. An example of an error is the `OutOfMemoryError` which occurs when an application is trying to use more memory than is available on the system.
 
-Like unchecked exceptions, errors are not checked at compile-time.
-They are not usually thrown from application code.
+Like unchecked exceptions, errors are not checked at compile-time and are not usually thrown from application code. Unlike exceptions, Errors represent serious system-level problems that applications should generally not attempt to catch or handle.
 
-All exceptions in Java that inherit from `Error` are considered errors.
+All errors in Java inherit from the `Error` class.
 
 ## Throwing exceptions
 

exercises/concept/calculator-conundrum/.docs/introduction.md

@@ -10,11 +10,10 @@ An exception is an event that occurs during the execution of a program that disr
 Exceptions are raised explicitly in Java, and the act of raising an exception is called _throwing an exception_.
 The act of handling an exception is called _catching an exception_.
 
-Java distinguishes three types of exceptions:
+Java distinguishes two types of exceptions:
 
 1. Checked exceptions
 2. Unchecked exceptions
-3. Errors
 
 #### Checked exceptions
 
@@ -23,7 +22,7 @@ An example of a checked exception is the `FileNotFoundException` which occurs wh
 
 This type of exception is checked at compile-time: methods that throw checked exceptions should specify this in their method signature, and code calling a method that might throw a checked exception is required to handle it or the code will not compile.
 
-All exceptions in Java that do not inherit from `RuntimeException` or `Error` are considered checked exceptions.
+All exceptions in Java that do not inherit from `RuntimeException` are checked exceptions.
 
 #### Unchecked exceptions
 
@@ -32,17 +31,15 @@ An example of an unchecked exception is the `NullPointerException` which occurs
 
 This type of exception is not checked at compile-time: methods that throw unchecked exceptions are not required to specify this in their method signature, and code calling a method that might throw an unchecked exception is not required to handle it.
 
-All exceptions in Java that inherit from `RuntimeException` are considered unchecked exceptions.
+All exceptions in Java that inherit from `RuntimeException` are unchecked exceptions.
 
-#### Errors
+### Errors
 
-_Errors_ are exceptional conditions that are external to an application.
-An example of an error is the `OutOfMemoryError` which occurs when an application is trying to use more memory than is available on the system.
+Java also has a separate category called _Errors_ which are serious problems that are external to an application. An example of an error is the `OutOfMemoryError` which occurs when an application is trying to use more memory than is available on the system.
 
-Like unchecked exceptions, errors are not checked at compile-time.
-They are not usually thrown from application code.
+Like unchecked exceptions, errors are not checked at compile-time and are not usually thrown from application code. Unlike exceptions, Errors represent serious system-level problems that applications should generally not attempt to catch or handle.
 
-All exceptions in Java that inherit from `Error` are considered errors.
+All errors in Java inherit from the `Error` class.
 
 ### Throwing exceptions