Elasticsearch is a full-text search engine based on the Apache Lucene library. The project is open source and developed in Java. Elasticsearch supports horizontal scaling, multitenancy, and clustering approaches. The fundamental element of Elasticsearch is its search index. This index is stored in forms of JSON internally. A single Elasticsearch server stores multiple indexes (each index represents a database), and a single query can search data with multiple indexes.
Elasticsearch can really provide near real-time searches and can scale with very low latency. The search and results programming model is exposed through the Elasticsearch API and available over HTTP.