What is SQL Server

SQL Server is a relational database management system provided by Microsoft .It has the following Variants i.e Developer Edition (Free) , Express Edition (Free) ,Standard Edition , Enterprise Edition . As of this writing , the latest version is Sql Server 2019

How Data Is stored in Sql Server

Sql stores data in files These files have extensions .mdf , .ndf,.ldf . i.e Primary , secondary and log files . Every database must have one primary data file . It may or may not have a secondary data file . There should be at least one log file . Log Files are required to recover the database.