Experience Manager uses projects to track and control changes that you and other users make to a site.

Think of a project as a working copy of your site. You can work alone in this copy or work with others in the same copy. Your organization can have several projects under development at the same time; each being an isolated working copy of the site. Any changes that you make in your project are not committed to a site until you publish your project. This published project is written or merged into your site, and all your updates become part of the current site. As other projects are published, your own project reflects any updates the team members of these other projects have made.