The NoSQL world
As social media became huge, data requirements increased too. The need to store and retrieve large amounts of data immediately, led to some companies involved in the problem to think about possible alternatives.
So, projects such as BigTable (Google) and Dynamo (Amazon) were among the first few attempts to find a solution to this problem. These projects encouraged a new movement that we now know as the NoSQL initiative, the term being proposed by Johan Oskarsson in a conference in California about these topics, for which he created the Twitter hashtag #NoSQL.
We can define the NoSQL movement as a broad class of system-management databases that differ from the classical model of relational databases (RDBMS) in important facets, the most noticeable one being that they are not using SQL as the primary query language.
Stored data does not require fixed structures such as tables. The result? They don't support JOIN operations, and they do not fully guarantee ACID (atomicity, consistency...