The term NoSQL has come to be synonymous with schema-less, non-relational data storage schemes. NoSQL is an umbrella term, one which encompasses a number of different technologies. These different technologies aren’t even necessarily related in any way beyond the single defining characteristic of NoSQL: they are not relational in nature; for right or wrong, Structured Query Language (SQL) has become conflated with relational database management systems over the years.
So, while I am not personally a fan of the term NoSQL, I can appreciate why others are, given that it quickly implies what it is we are talking about by explicitly stating what we are not talking about. As such, I grin and bear its usage.
On the implementation side, the most popular NoSQL Database Engines todaycan be found here. But if you’re interested in learning more about the NoSQL world, keep reading below.