The Features list provides access to all features you can place in the map as well as various types of favorites. The list remains empty until you have an edit session started. You can begin an edit session using Esri's Editor toolbar (select Editor > Start Editing).
The contents of the Features list are grouped into several categories: System Favorites, User Favorites, Feature Classes and Tables.
System Favorites: Contains the favorites available to all users in the geodatabase. These favorites may include some that may not be placed in your current map. For example, if your map contains only electric features, you may not place a favorite that contains gas layers.
User Favorites: Contains the favorites available only to the current user. The current user name is displayed in parentheses next to the User Favorites node. Like System Favorites, these favorites may include some that cannot be placed in the current map.
Feature Classes: Contains the spatial features you can place on the map.
Tables: Contains the non-spatial tables (or object classes) that may be related to features (related objects).
Navigation: You can expand and contract nodes on the Features list by clicking the plus/minus signs. If you want to expand or collapse multiple nodes at once, select the top-most node (of those you want to expand/collapse) and press the asterisk (*) symbol (expand) or the minus (-) symbol (collapse) on your keyboard number pad. The asterisk (shift + 8) and the minus on the main keyboard will not work. You must use the * and - above the number pad on your keyboard. This functionality also works on the Attribute Editor tabs.