By now you should have a taste of what you can do with Elasticsearch, and how easy it is to get started. Elasticsearch tries hard to work out of the box with minimal knowledge and configuration. The best way to learn Elasticsearch is by jumping in: just start indexing and searching!
However, the more you know about Elasticsearch, the more productive you can become. The more you can tell Elasticsearch about the domain-specific elements of your application, the more you can fine-tune the output.
The rest of this book will help you move from novice to expert. Each chapter explains the essentials, but also includes expert-level tips. If you’re just getting started, these tips are probably not immediately relevant to you; Elasticsearch has sensible defaults and will generally do the right thing without any interference. You can always revisit these chapters later, when you are looking to improve performance by shaving off any wasted milliseconds.