Revision is a feature in Drupal that allows content creators to track changes to their content over time. It allows content creators to save multiple versions of their content, and to compare and restore previous versions if needed. This feature is especially useful for content that is frequently updated, such as news articles or blog posts.

When a content creator saves a new version of their content, a new revision is created. Each revision is stored in the database and can be accessed from the content's edit page. The revisions are listed in chronological order, with the most recent revision at the top. Content creators can compare two revisions side-by-side, or restore a previous revision if needed.

Revision is an important feature in Drupal, as it allows content creators to keep track of changes to their content over time. It also allows them to easily restore previous versions of their content if needed.