This chapter introduces SQL (Structured Query Language) as the standard language for relational database management systems. It discusses the history and development of SQL, the SQL standards, and the basic components and statements in SQL for defining schemas, querying and manipulating data, and enforcing data integrity. These include the data definition language (DDL) for creating tables, the data manipulation language (DML) for queries, inserts, updates and deletes, and data control language (DCL) for security. Examples are provided to illustrate how to define tables and relationships, and write queries using SQL statements.