CouchDB is an open-source NoSQL document-oriented database that collects and stores data in JSON-based document formats. It was first released in 2005 and later became an Apache Software Foundation project in 2008. CouchDB uses multiple formats and protocols to store, transfer, and process its data. It uses JSON to store data, JavaScript as its query language using MapReduce, and HTTP for an API. Some key features of CouchDB include:

• Document Storage: CouchDB stores data in JSON-based documents, which are uniquely named in the database. Each document maintains its own data and self-contained schema.

• Replication: CouchDB provides easy-to-use replication, using which you can copy, share, and synchronize the data between databases and machines.

• ACID Properties: CouchDB follows all the features of ACID properties.

• Security: CouchDB provides security features such as user authentication and authorization.

CouchDB is a multi-master application that can be used as a single-node database or as a clustered database that allows you to run a single logical database server on any number of servers or VMs. CouchDB is built on the Erlang programming language and is designed to work with the ubiquitous HTTP protocol and JSON data format. CouchDB is used by various organizations such as CERN, Red Cross, IBM Cloud services, United Airlines, and Amadeus IT Group.