It's mashed or pureed chick peas with seasonings and usually tahini paste (which is made much like peanut butter, but usually thinner and made from sesame seeds instead of peanuts). You can make it at home or buy it already prepared (Walmarts usually carry it and I usually see it by the deli counter, in the case with prepared salads and sandwhiches, gourmet mustards stuff like that.
I've only seen it as a smooth dip, but I recently saw one of Rachel Ray's restaurant review shows, and a middle eastern restaurant served theirs at the table, and it was more like a chickpea salad (chick peas, onions, cilantro and a vinaigrette) that was only slightly mashed up instead of purreed smooth.
I make mine at home in a food processor. 1 can of drained chickpeas, a little bit of salt, lemon and fresh garlic. That's all I use.
I also make a similar dip from a can of beans (anything from pintos, white beans, and even baked beans make really good dips).