By popular request, this is a picture of the two-position wooden chair that we use in our libraries for study seating. They are designed to be tipped back, the way everyone seems to like to sit. In a regular four-legged chair, this can put a lot of pressure on the back legs and they can break. We have had students break a few of these chairs in our 24-hour lounge, we think by jumping on them (the seat supports broke under the cushions). They do slide on carpet, but they are heavy.
