Recently NoSQL has gained immense popularity.
What are the advantages of NoSQL over traditional RDBMS?
Not all data is relational. For those situations, NoSQL can be helpful.
With that said, NoSQL stands for "Not Only SQL". It's not intended to knock SQL or supplant it.
SQL has several very big advantages:
Those haven't gone away.
It's a mistake to think about this as an either/or argument. NoSQL is an alternative that people need to consider when it fits, that's all.
Documents can be stored in non-relational databases, like CouchDB.
Maybe reading this will help.