NoSQL
NoSQL means Not-only SQL, and not NO-SQL. Normally referring to a JSON based database, also known as Document based Database.
Unlike SQL, data is not sorted in a table representing Columns and Rows, but rather as KVP in a JSON structure.
NoSQL is schemaless, which means you don’t require schemas. This is why there is a debate about whether MongooseJS is actually an anti-pattern.
No schema, doesnt mean you can validate the data
Difference between SQL and NoSQL Database
The main difference between SQL and NoSQL databases is integrity and flexibility.
SQL Database are inflexible, but provide integrity
NoSQL Database are flexible, but the data integrity is up to the developer.
References
[MongooseJS Anti-Pattern]
Relational Models