SharePoint features provide functionality to make SharePoint more useful. Features are containers of extensions that can be bundled in site definitions or enabled individually on sites. They include XML files deployed to web front ends and can include custom fields, lists, and web parts. For example, a "My Favorite Items" feature may create a hidden favorites list per user when enabled, add a custom "Add to Favorites" menu item to all lists, and include a web part to display the user's top 10 favorites.