Elasticsearch Fundamentals

Elasticsearch is a distributed search and analytics engine. It is also a scalable data store and vector database built on Apache Lucene. You send it documents, then search or analyze those documents through HTTP APIs.

Think of Elasticsearch as a retrieval system, not a general replacement for every transactional database. It is strongest when you need to find relevant records, filter a large data set, or summarize it. Product search, log analysis, security events, and operational metrics are common fits.

The mental model

An index is the named collection that holds documents. A document is a JSON object that you index into that collection. A mapping describes how Elasticsearch interprets fields. Field choices shape what you can search, sort, aggregate, and filter.