Edit Keys displays your animation as a series of keys, displayed as boxes on a grid in the Key window. This tool is available only in Dope Sheet mode, where it is active by default. The alternative Dope Sheet modes are Edit Ranges and Edit Time.
Edit Keys is useful for getting a global view of your animation because it displays animation timing for all tracks. Use this mode for key and range editing when you want to view your changes in the context of the total animation.
To activate Edit Keys mode, do one of the following:
Dope Sheet.
(Edit Ranges) mode is active, then on the Keys toolbar, click 
(Edit Keys).
To delete keys in Edit Keys mode:
Use the Edit Time tools to work directly with selected blocks of time in the Dope Sheet Editor, as opposed to working with keys and range bars. A block of time is any contiguous time segment, across one or more tracks, and is independent of key locations.
Edit Ranges displays all tracks as range bars. This mode is useful for quickly scaling and sliding complete animation tracks.
