[[NoSQL]]

[[NoSQL]] (sometimes expanded to "not only SQL") is a broad class of database management systems that differ from the classic model of the relational database management system (RDBMS) in some significant ways. These data stores may not require fixed table schemas, usually avoid join operations, and typically scale horizontally. Academic researchers typically refer to these databases as structured storage, a term that includes classic relational databases as a subset.

source: http://en.wikipedia.org/wiki/NoSQL

ref. also: http://nosql-database.org/