In defining the space of NoSQL, let's first take a stab at defining the name. Taken literally, a NoSQL system presents a query interface to the user that is not SQL. The NoSQL community generally takes a more inclusive view, suggesting that NoSQL systems provide alternatives to traditional relational databases, and allow developers to design projects which use Not Only a SQL interface. In some cases, you might replace a relational database with a NoSQL alternative, and in others you will employ a mix-and-match approach to different problems you encounter in application development.