What is sds drill?

The SDS system is used on drills that drill through stuff like concrete. The bit has a standard size male part with four grooves in it. The drill chuck has four fingers that mate with the grooves on the bit shank. To change bits you just pull the old one out of the drill with your hand and push the new one into the chuck. It's very slick. They even sell a Jacobs-style jaw chuck adapter for it, so you can use all your non-SDS bits with an SDS drill.