There's no two ways about it: your common or garden sprinkler (so garden, in all probability) is a blithering half-wit. Rain or no, if you don't turn it off, it'll water your lawn whether it needs it or not, and much more besides. The Droplet wants to change all that. A sort of "smart" water cannon, it knows which parts of your garden to water, and when.
Read the full article: Dead-eye Droplet: The assassin of garden sprinklers