A tent ( (listen)) is a shelter consisting of sheets of fabric or other material draped over, attached to a frame of poles or attached to a supporting rope. While smaller tents may be free-standing or attached to the ground, large tents are usually anchored using guy ropes tied to stakes or tent pegs. First used as portable homes by nomads, tents are now more often used for recreational camping and as temporary shelters. A form of tent called a teepee or tipi, noted for its cone shape and peak smoke-hole, was also used by Native American tribes and Aboriginal Canadians of the Plains Indians since ancient times, variously estimated from 10,000 years BCE to 4,000 BCE.Tents range in size from "bivouac" structures, just big enough for one person to sleep in, up to huge circus tents capable of seating thousands of people. Tents for recreational camping fall into two categories. Tents intended to be carried by backpackers are the smallest and lightest type. Small tents may be sufficiently light that they can be carried for long distances on a touring bicycle, a boat, or when backpacking. The second type are larger, heavier tents which are usually carried in a car or other vehicle. Depending on tent size and the experience of the person or people involved, such tents can usually be assembled (pitched) in between 5 and 25 minutes; disassembly (striking) takes a similar length of time. Some very specialised tents have spring-loaded poles and can be pitched in seconds, but take somewhat longer to strike (take down and pack).