The dopesheet
The dopesheet only shows time information for keys. Individual keys and groups of keys can be scaled and moved. These operations are also available in the channel editor. However, the dopesheet makes it more convenient to work on large numbers of channels and keys.
In the screenshot above, the keys in a single channel are being scaled. The vertical red lines are anchors for the scaling operation. Dragging on one anchor stretches the time spacing of the keys, with the key at the other anchor remaining fixed.