Elasticsearch is at the heart of the Elastic Stack. It stores all your data and provides search and analytic capabilities in a scalable way. We have already looked at the strengths of Elasticsearch and why you would want to use it. Elasticsearch can be used without using any other components to power your application in terms of search and analytics. We will cover Elasticsearch in great detail in Chapter 2, Getting Started with Elasticsearch, Chapter 3, Searching-What is Relevant, and Chapter 4, Analytics with Elasticsearch.