What is the function of a JOIN operation in SQL?

The function of a JOIN operation in SQL is to combine columns from two or more tables based on a related column between them. This allows for more complex queries that can extract data from multiple sources in a relational database, resulting in a unified dataset that can be analyzed or displayed together.

Using JOINs, you can retrieve data that is normalized across several tables without having to duplicate records. For example, if you have a 'Customers' table and an 'Orders' table, a JOIN operation can help you effectively display information about each customer alongside their corresponding orders. This capability is critical in relational database management, as it enhances data retrieval efficiency and supports robust data relationships.

The other options provided do not capture the essence of what JOIN operations do in SQL. While categorizing records is a function of database management, it's not related to JOINs. Sorting records pertains to the ORDER BY clause, not JOINs. Deleting records is handled by the DELETE statement, which is a distinct operation in SQL.