What does an ORDER BY clause do in a SELECT query?

The ORDER BY clause in a SELECT query is used to define the sorting order of the results returned from the query. When you include this clause, you can specify one or more columns by which the results should be ordered, either in ascending or descending order. For example, if you're retrieving a list of names from a database and you want them sorted alphabetically, you can use ORDER BY to achieve that. This functionality enhances readability and allows users to easily find specific records that meet their needs.

The other options represent different aspects of SQL queries. Altering the data structure pertains to Data Definition Language (DDL) commands rather than the ORDER BY clause. Specifying conditions for inclusion is related to the WHERE clause, which filters records based on defined criteria. Selecting which columns to display corresponds to the SELECT statement itself, which determines what data will be included in the output. Hence, the choice of defining how results are sorted distinctly aligns with the purpose of the ORDER BY clause in SQL.