Olympic Swimming Relays

My wife and I got really confused as to how the swimming relay exchanges are handled. As nobody on NBC bothered to explain it, I had to do some research and here it is.

Basically, swimmers can (and should) be in motion during the relay exchanges, but the outgoing swimmer must maintain contact with the starting platform until the incoming swimmer has finished. The incoming swimmer's finish is registered by the electronic touchpad on the finishing wall, as is the outgoing swimmer's contact with the starting platform. The two times are compared by an electronic timing system (with a .03 second "allowance"), and if the outgoing swimmer is off the platform early, that team is disqualified.

The above also explains why only the first leg of any swim relay counts towards official records, as it is the only leg that is comparable to a non-relay race.