The Outliner is one of two main scene management editors in Maya (the other is the Hypergraph).
The Outliner shows the hierarchy of all objects in the scene in outline form: You can expand and collapse the display of branches in the hierarchy, and lower levels of the hierarchy are indented under higher levels.
The Outliner includes objects that are normally hidden in the view panels, such as the default cameras. You can control what objects appear in the Outliner using the menus and the text filter box. For example, type *top* in the box and press to only show objects with the letters top in their names.
Clicking the name of a node in the Outliner selects the node. The selected node(s) are shown with a gray background. You can double-click the name of a node to rename it.
You use the Outliner most often for two functions: