A form of movement designed to explore the limits and preferences of the human body.
Well, Contact Improv is difficult to define. To the spectator, it might look like friendly people rolling around on the floor with each other. One of the major (malleable) rules is that you keep physical contact with your partner at all times. Contact is generally a duet form, it's easiest to connect to one person at a time, though often trios or clumps or four or more may form. Solo contact is difficult to achieve convincingly. With no partner to bounce ideas off of, it loses power, gets fancy looking. Contact is not so much about looks.
A good contact session, or jam, starts with a good warmup. This should be something in between an aerobics warmup and a meditation session. The point is to drop the ugly, heavy and stinking you've been carrying around, and start to discover what your body feels like, to pay attention to how your body is at rest, and gradually, how it is in motion. This is a grounding exercise, so that before you get mixed up with other people's weight(and energy), you tune in to your own.
After warming up, people come together and "jam" for a while. This looks like twisting, hugging, rolling, climbing, crawling, and exploring movement. This is the stage where duets (and clumps) form. Sometimes a structured exercise will follow, where the facilitator will introduce a set of rules, and let the contactors work around them.
Contact is what you make it. Practitioners of contact improv call it dance, and play. Contactors come in all ages, colors and flavors, and convene to find new bodies. Usually these meet-ups take place in a major city, or within a couple hours' drive. Room and board is put forth by host contactors who are native to the area and have opened their homes.
There is a strange trust that comes from surrendering your weight to another person, and then providing your strength when she surrenders hers to you. Some of the heavily ingrained social barriers seem to disappear in the dance-space. During my first experience with contact, I was wisely advised to "Feel the ground through your partner." Once you "get" this, it becomes hard to ignore in mundane places. I've met fellow contactors in various environments and our greeting is always physical, even before we start introducing each other and explaining, our closest body parts seem pulled together by some understated gravity.
Contact is all about finding edges to push and pull. Contact is all about going places where your body is comfortable, where it needs to go, where it could've been years ago if you'd just stop resisting. Contact is all about using your mind for something different than thinking. Contact is hard to describe. It just kinda happens.