Final answer:
The JOIN command is used in the FROM clause to combine records from two tables with matching values in a common field in SQL databases.
Step-by-step explanation:
The JOIN command is used in any FROM clause to combine records from two tables whenever there are matching values in a common field. This command is essential in SQL, a common language for managing and querying databases. A JOIN can be of various types, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN, each serving a specific purpose in combining records from multiple tables.