SelectionNamespace: UnityEditor

activeGameObject	Returns the active game object. (The one shown in the inspector).
activeInstanceID	Returns the instanceID of the actual object selection. Includes prefabs, non-modifyable objects.
activeObject	Returns the actual object selection. Includes prefabs, non-modifyable objects.
activeTransform	Returns the active transform. (The one shown in the inspector).
gameObjects	Returns the actual game object selection. Includes prefabs, non-modifyable objects.
instanceIDs	The actual unfiltered selection from the Scene returned as instance ids instead of objects.
objects	The actual unfiltered selection from the Scene.
transforms	Returns the top level selection, excluding prefabs.

Contains	Returns whether an object is contained in the current selection.
GetFiltered	Returns the current selection filtered by type and mode.
GetTransforms	Allows for fine grained control of the selection type using the SelectionMode bitmask.