The PDOStatement class is part of the PHP Data Objects (PDO) extension, which provides a consistent interface for accessing databases in PHP. A PDOStatement object represents a prepared statement and is used to execute SQL queries securely. It helps prevent SQL injection attacks by separating SQL logic from user input. When you prepare a statement using PDO, it returns a PDOStatement object that you can execute multiple times with different parameters. This enhances performance and security, as the SQL query is compiled only once. You can also fetch results and manage transactions using the methods provided by the PDOStatement class.