In 1992 at Yale University, a group of loony undergraduates with nothing better to do with their free time than whap each other over the head with silly foam swords founded The Freestyle Dueling Association. They decided that the obvious course of action was to found a club, so that they would be recognized, get a website, and best of all get funding.
They had a bunch of gaming experience, a lot of spare time, actually loads of spare time, decided that the tabletop experience was just not enough. They wanted more... They wanted to be able to relieve aggressions without hurting anyone (well, at least not very permanently), and to be able to make bad Monty Python references, to hack and slash at things like trolls, werewolves, skeletons, CRUNCHIES! They wanted to create the Freestyle Dueling Assocation (FDA).
The main purpose of the FDA is to have fun. We fight with swords made from a fiberglass core covered in foam, generally some type of mattress padding or equivalent. Because the swords are somewhat soft, they will not hurt the victim when he or she is mercilessly beaten for hours at a time. Ahem.
Although we need no armor or other serious protection (see the Society for Creative Anachronism (SCA) for more realistic stuff), we still avoid hitting to the head and groin areas, for although legal and somewhat safe, they're just not fun. Trust me.
Many people refer to the type of weapons we use as boffers or foam boffers. On campus we are known as the foam-sword people, though we also have parry staves, shields, a bow and arrow set, and even some wacky things like a flail and morning star. The 'sport' we practice comes from a live action fantasy roleplaying game called Quest, which almost solely existent in Connecticut.
Dan Fabulich deserves credit for descriptions and guidance with the Freestyle Dueling Associaton