SQL is a powerful special purpose programming language that works to ensure a number of the modern technologies that we rely on today run consistently and smoothly. This language type is designed to manage data held in a RDBMS (Relational Database Management System). Being a relational database engine was SQL's original purpose but it has since grown to include a number of new database technologies, such as Relational Data Stream Management System (RDSMS).
In reality more people work with SQL Server in their day to day tasks than anyone probably realises. Many web sites and core business applications are supported by SQL Server. Typically SQL Server based applications are designed, built, maintained and enhanced by DBAs, Developers, Data Modellers, Network Admins, System Admins, Storage Admins, etc.