What does it mean for a database to be relational?

A relational database is a type of database in which data is organized into tables (relations). Each table consists of rows and columns, where rows represent records and columns are fields with specific data types. The main idea of the relational model is to store data in related tables using keys (primary and foreign), which ensures integrity and allows complex queries using SQL. For example, a "Users" table can be related to an "Orders" table through the foreign key "user_id".