PHP Data Objects (PDO) is a database access layer that provides a uniform method for interacting with various databases in PHP. It allows developers to execute SQL queries, retrieve data, and manage database connections in a consistent way, regardless of the underlying database system. One of the key features of PDO is its support for prepared statements, which enhance security by preventing SQL injection attacks. Additionally, PDO offers a flexible error handling mechanism and supports multiple database types, making it a versatile choice for developers working with different database management systems.