The era of Polyglot Persistence has begun. The emergence of NoSQL databases alarms the end of the dominance of Relational databases. NoSQL = Not only SQL surly not to replace relational databases, rather, it gives more convenience to the developers to have database design with elastic nature for their projects. Relational data models will still be popular, however, will no longer be the automatic choice. To take advantage of this paradigm change, one need to be familiar with the underlying concepts of NoSQL to become Data professionals. Because, Data professionals should be familiar with these different approaches to know how to match them for their solutions. NoSQL introduces the new ways of data modeling, data consistency and data evolution. This book surly helps the developers to learn and cherish the power of NoSQL in building their representative systems using this new technique. This book gives an introductory to the underlying concepts of NoSQL such as, implementation of CAP theorem in various NoSQL databases, different data storage techniques along with the brief outline of two major document store NoSQL databases such as, MongoDB and CouchDB.