SQL (Structured Query Language) is a programming language that is used to manage relational databases. It is a standard language used to communicate with databases and used by many database systems, including MySQL, Oracle, Microsoft SQL Server, and PostgreSQL.

SQL is a declarative language, which means that it allows users to specify what data they want to retrieve or manipulate from the database without having to specify how to do it.

SQL is used for various purposes, including querying data, updating data, adding new data to a database, and deleting data from a database. It allows users to create and modify database schemas and to define relationships between tables. It is also used for data analysis and reporting and can be used to create views, which are virtual tables representing a subset of the data in a database.