In a database, what is a key used for?

A key in a database serves a critical function in identifying records, particularly when searching and sorting data. A primary key uniquely identifies each record in a table, ensuring that each entry can be precisely located without ambiguity. This unique identification is essential for operations that retrieve, update, or delete records, as it allows the database to find the correct entry quickly and efficiently.

Additionally, when sorting data, the key plays a crucial role in determining the order of records, enabling organized and accessible data structures. The effectiveness of keys in identifying and retrieving records streamlines various database operations, ultimately contributing to efficient data management.

While the other options touch on important aspects of database design and management—such as creating relationships, managing user access, and maintaining data integrity—the distinctive purpose of a key primarily revolves around record identification and retrieval processes.