A sprinkler timer is used to turn a lawn sprinkler on and off automatically. If you just want to be able to have it come on at a certain time of the day and shut off again at a later time then an automatic sprinkler timer should do just fine. However, different areas of your lawn and garden have different water requirements.
Suppose that you need one part of your lawn watered every other day for twenty minutes and another part needs watered every day for ten minutes. This can be easily accomplished through programmable sprinkler controls.