There are several popular types of wigs.
Fiber wigs are made with synthetic fibers attached to a wig cap. They come in a wide variety of colors, lengths, and styles and are available from most doll distributors. They are the most common type of wig for BJD.
Heat-resistant fiber wigs can be styled or curled using heat.
'Mohair' can refer to several types of wigs. Some are made by using the skins of goats or sheep that have the fur still attached; others use wefts of fur or wool from these animals sewn to an cloth wig cap.
These wigs are characteristically soft, full, and curly.
Some Asian companies inaccurately refer to fur wigs as mohair. [Due to the fact that "mo" is fur in Cantonese, Chinese.]
Most fur wigs are made using synthetic craft furs rather than animal fur. Simple fur wigs may be made from 2 half-circles of craft fur, while more complex wigs may be made from many smaller pieces with elaborate darts and seams to alter the fit and style. Higher quality fur wigs tend to be hemmed around the edge for a more finished look.
Though somewhat uncommon, occasionally human hairs are used to make the wigs for dolls. As such, they have the major advantage of having the same versatility as regular human hair; bleach, perm, coloring, curling, styling, etc. but also have the same problems that can come with it as well such as split ends, frizz, etc. Human hair will also generally lay better against the doll's head (depending on how coarse it is) and look the most natural.