The general term "cashmere goat" refers to a type of goat that produces fiber meeting the international standard for cashmere, rather than a breed. However, the Cashmere Goat Association has established a more detailed standard for cashmere goats and the USDA has recently recognized "North American Cashmere Goats" as a breed of cashmere goats who meet that standard. You can find more information about the standard and a registry for cashmere goats on the Cashmere Goat Association website.
Cashmere goats produce a downy undercoat, one of the finest in the world, that can be combed out in early spring as the goat naturally sheds it. They are judged on their ability to produce fleeces that are very fine in diameter, long enough to be easily spun and to avoid producing "pilling" in garments, and crimpy in style. Cashmere goats are dual-purpose animals, providing both fiber and meat, and they are thoroughly satisfying animals to raise - funny, individual, energetic, and often very friendly.