SOL (Structured Query Language) is a special- purpose language developed to work with relational databases. More specifically it's used to manage and manipulate data in those databases, While SQL won't be used to write the next big web application it's useful in interacting with the database that would power that application. If you plan on managing servers, or creating your own server, SQL programming language will most certainly prove useful. Many servers use databases ike MySQL or SQL Server to, well, store data