There exist two principal weave structures: flat weave and knotted pile. Flat-woven fabrics such as kilims, consist simply of a warp (vertical) yarn and weft (horizontal) yarn. Patterns are created by limiting the weft yarn of certain colours to certain areas. The technique is especially suitable to geometric, rather than curvilinear, designs. Flat-woven carpets, for instance, may be embellished by brocading (introducing supplementary warps or wefts to create a pattern) or by the needlework technique of embroidery. Knotted pile fabrics consist of a foundation of flat-woven yarns to which a knotted pile is added on the loom. The pile is constructed by wrapping or knotting short individual strands around the warp threads. After each row is knotted, a weft thread is carried across the full width of the web and beaten firmly into place with a heavy comb. As an area is completed, the knotted strands are sheared to create an even pile in plain weave. The history of weave structures encompasses two major traditions, the Oriental and the Western. The older and richer is the Oriental tradition, which includes the work of Central Asian, Middle Eastern, North African, subcontinental Indian, and Chinese artisans. The Western tradition, derived from the Oriental, was established much later. It enjoyed a brief period of originality in France in the 17th and 18th centuries, but succumbed to imitation and to mechanical weaving. The 18th century was the time of transformation of old techniques to modern industry. Woven textiles differ in weave structures, that is in the very technique of weaving. Everything depends on the way the weft and the warp cross each other. Three fundamental techniques are used: plain weave, twill weave and satin weave. Plain weave is also called tabby, calico or taffeta. These are most simple weave structures with the help of which cheap fabrics, printed designs and heavy yarns are made. However, the technique may have some variations, for example, the use of some yarns or the combination of coarse and fine yarns. This produces corded and ribbed fabrics, such as dimity, rep, poplin and grosgrain. The second method, which is considered to be primary one, - twill weave. Its variations are corkscrew designs and herringbone. Twill textiles are gabardine, drill, serge and denim which are famous for their close firm weave. And the last method is satin weave, which is characterised by luster and reflects light. Weaving was prohibited in colonial America by the British. Colonists were obliged to dispatch flax and cotton to Britain and to buy finished goods from England afterwards. Nonetheless many Americans wove textile in their country. Flax and cotton were particularly common there, because the British not willing to send wool or ship to their colonies. They gathered the crops of cotton in autumn and the crops of flax in summer. Later colonists of America started rearing their sheep. They normally sheared the sheep in spring, so that the wool could regrow till winter. After that the wool was washed and cleaned from dirt. Then it was carded and spinned into yarn. A card is comprised of two brushes. It lines up fibres in the same direction making them ready for spinning. In order to prepare flax for the procedure of weaving, it was necessary to beat the stalks, to pull them through a comb thus making it ready for spinning.Plain weave was extremely popular in America in colonial time. Almost all weave structure fabrics were made by this very method. Sometimes they added designs , but usually that was done after weaving. Colonists did it with the help of wooden block prints or by means of embroidering.