The Rise of NoSQL data stores

NoSQL is a movement promoting a loosely defined class of non-relational data stores that break with a long history of relational databases. These data stores may not require fixed table schemas, usually avoid join operations and typically scale horizontally.
Basically the data won't be stored as table/matrix as most of us have come to know how a basic DB looks like.Relational data is easy to understand for most applications but scalability & performance take a hit or its a trade off between convention over being faster & large.
Data processing performance & scalability,as most CS graduates would agree, is hugely influenced by underlying data structures like map,trees,graphs etc.The NoSQL movement is gaining traction due to the toll man's principle "Using the right tools for the right job"

If it further interests you explore http://en.wikipedia.org/wiki/NoSQL