PDO stands for PHP Data Object. It is a lean and consistent way to access databases. It facilitates developers to write portable codes easily. PDO is not an abstraction layer. It is more like a data access layer which uses a unified API.

In Drupal, PDO stands for PHP Data Objects. PDO is a database access layer providing a uniform method of access to multiple databases. It is a PHP extension that provides a lightweight, consistent interface for accessing databases in Drupal. PDO offers a flexible and secure way to interact with databases, allowing Drupal developers to write database-independent code easily. It supports various database systems such as MySQL, PostgreSQL, SQLite, etc., making Drupal applications more portable and scalable.