What exactly is emergency contraception?

Excellent question Zcat.  I found a really helpful directory of information on womenshealth.gov that covers both of those questions and more very well.  It is my opinion that every woman who is not trying to become pregnant should have emergency contraception on hand.  You never know when a condom will break or a diaphragm or sponge might slip or you just forget to use your normal method of birth control.  Better safe than sorry I say.