The SQL BETWEEN operator is used to select rows that are within a specific range, inclusive of the start and end values. It can be used with numbers, text, and dates, and is commonly used in scenarios where data needs to be filtered by a specific time range or numeric value. The operator is usually placed after the WHERE clause and can be used to filter data outside a specified range using the NOT BETWEEN operator. Additionally, the BETWEEN operator can be combined with other operators like IN to achieve more complex filtering conditions.