Addressing the need to store and manage increasingly large amounts of data that does not fit neatly in rows and columns, NoSQL databases can run on commodity hardware, support the unstructured, non-relational data flowing into organizations from the proliferation of new sources, and are available in a variety of structures that open up new types of data sources, providing ways to tap into the institutional knowledge locked in PCs and departmental silos.
The four key database types that fall under the NoSQL category are Key-Value stores which allow the storage of schema-less data, with a key and actual data, Column family databases, which store data within columns, Graph databases which employ structures with nodes, edges and properties to store data, and Document Databases, which enable simple storage of document aggregates.
Look to NoSQL for fast, highly scalable access to free-form data. This comes with a few costs, like consistency of reads and other safeguards common to SQL databases. But for many applications, those safeguards may well be worth trading for what NoSQL offers.
Best NoSQL Database
MongoDB
Finalists
Couchbase
Redis