Microsoft SQL Server is a Relational Database Management System (RDBMS) developed by Microsoft. It is a highly scalable product that can be run on anything from a single laptop, to a network of high-powered cloud servers, and anything in between.

Of course, by "anything", it still needs to satisfy the usual hardware and software requirements, but these requirements are reasonably modest, considering what SQL Server is capable of.
According to Microsoft, SQL Server is the number 1 most-used database in the world. According to various other sources, it's more like number 2, 3, or 4. In any case, it's one of the most popular database management systems in the world.
Since the release of SQL Server 1.0 in 1989, SQL Server has evolved to become a true, enterprise information platform. While it's core function is that of an RDBMS, SQL Server has become much more than that. SQL Server 2016 includes built-in business intelligence tools, as well as a range of analysis and reporting tools. This is on top of the database management tools such as database creation, backup, replication, security, and more.
This tutorial focuses more on the database management tools.

Complete Tutorial:-