ElasticSearch : is a distributed Restful search and analytics Engine, which is used to provide Enterprise search, Observability and Security all under with the same stack. It gives Availability and Partition tolerance of CAP theorem and Consistency can be achieved with multiple tricks. The elastic stack ELK is : Elastic Search Integrations(Log stash) Kibana (UI dashboard to visualise and manage the data) Elastic search is based on Lucene Library (open source) which is written in JAVA. The data can be stored anywhere, private or public or hybrid cloud. The elastic search uses sharding(primary and replica shards for documents), Index and run as multiple instances(Nodes) as a cluster to provide HA and Partition tolerance. The search queries in elastic search can be easy once as well as complicated. To create a quick index: PUT /bookdb_index { "settings": { "number_of_shards": 1 }} A quick example of a simple JSON query is : GET /bookdb_index/book/_search?q=guide ...