This document discusses NoSQL databases and provides examples of different types. It begins by discussing motivations for NoSQL like performance, scalability, and flexibility over traditional relational databases. It then categorizes NoSQL databases as key-value stores like Redis and Tokyo Cabinet, column-oriented stores like BigTable and Cassandra, document-oriented stores like CouchDB and MongoDB, and graph databases like Neo4J. For each category it provides comparisons on attributes and examples using different languages.