The Society for Creative Anachronism, or SCA, is an international organization dedicated to researching and re-creating the arts, skills, and traditions of pre-17th-century Europe.
Members of the SCA study and take part in a variety of activities, including combat, archery, equestrian activities, costuming, cooking, metalwork, woodworking, music, dance, calligraphy, fiber arts, and much more. If it was done in the Middle Ages or Renaissance, odds are you'll find someone in the SCA interested in recreating it.
What makes the SCA different from a Humanities 101 class is the active participation in the learning process. To learn about the clothing of the period, you research it, then sew and wear it yourself. To learn about combat, you put on armor (which you may have built yourself) and learn how to defeat your opponent. To learn brewing, you make (and sample!) your own wines, meads and beers.
You will frequently hear SCA participants describe the SCA as recreating the Middle Ages "as they ought to have been." In some ways this is true – we choose to use indoor plumbing, heated halls, and sewing machines. In the dead of winter we have more to eat than King's venison, salt pork and dried tubers. However, a better description is that we selectively recreate the culture, choosing elements of the culture that interest and attract us.
The SCA started in 1966, when a few friends who were history buffs and science fiction/fantasy fans hosted a big outdoor party in Berkeley, California. The invitation stated that a Tournament would be held on the first of May, summoning "all knights to defend in single combat the title of 'fairest' for their ladies."
Everyone enjoyed the first tournament so much that they agreed a second should be run, but in a larger setting. In order to reserve one of the public parks for the gathering, the organizers needed to list a name for their group on the application. Since recreating the Middle Ages in 20th-century Berkeley was an anachronism (something "out of time"), and because the goal was creativity, they came up with "The Society for Creative Anachronism". It was a spur-of-the-moment invention; they had no idea that the name would stay with their group into the future.
Word of the SCA spread via friends and science-fiction fandom. There were 6 events held in the first year, and 9 in the second. In the third year, a chapter was founded on the East Coast (the East Kingdom – distinguishing it from the West Kingdom); the Californians incorporated the SCA as a non-profit educational society, and away they went. Since 1966, the Society has grown to nineteen kingdoms, which cover the U.S., Canada, Europe, Asia, South Africa, and Australia. There are over 30,000 paid members of the corporation, and the total number of participants is around 60,000 people.