There are many types of warts, but chief among them is the common wart, and it is exactly that, common.
Warts are caused by the Human Papilloma Virus, or when shortened, HPV, depending on the type of wart, it could be a different strain of the HPV virus.
Some of the types of warts that exist today are:
Female Genital Warts
For Information on Each: Warts