[Solutions] Write overall solutions and use case landing page (#501)

Author: leemthompo

solutions/index.md

@@ -1,3 +1,33 @@
+---
+applies_to:
+  stack: ga
+  serverless: ga
+---
+
 # Solutions and use cases
 
-% What needs to be done: Write from scratch
+:::{tip}
+New to Elastic? Refer to [get started](/get-started/the-stack.md) to understand the Elastic Stack and its components, and your deployment options.
+:::
+
+Users reach for Elastic products, features, and tools for three main use cases: observability, security, and search.
+
+These use cases are supported by ready-to-use implementations that help you get started quickly:
+- As integrated solutions on [{{ecloud}} Hosted](/deploy-manage/deploy/elastic-cloud/cloud-hosted.md) and [self-managed](/deploy-manage/deploy/self-managed.md) deployments
+- As project types on [{{serverless-full}}](/deploy-manage/deploy/elastic-cloud/serverless.md)
+
+While these solutions and project types provide pre-built components for common use cases, you can also build custom implementations using Elastic's features, APIs, and tools. This documentation guides you through:
+
+1. Evaluating if an Elastic solution fits your needs
+2. Getting started with your chosen solution
+3. Implementing specific features and capabilities
+
+## Solution and use case documentation
+
+Learn more in the following sections:
+
+| Solution | Use case | 
+| --- | --- | 
+| [Observability](observability.md) | Monitor and troubleshoot applications and infrastructure with Elastic Observability
+| [Security](security.md) | Protect applications and infrastructure with Elastic Security
+| [Search](search.md) | Build search experiences, or implement custom use cases with Elasticsearch