Despite what your parents may have told you, you don't get warts from frogs. Contrary to popular belief, warts are actually caused by the human papillomavirus (HPV). [source: WebMD]. Although they can be unsightly and uncomfortable, warts are generally harmless. They form when HPV forces your body to make excess skin cells. This seems innocuous, but there's no place for those cells to go; as a result, they form bumps on your skin or grow inward, which can be painful.
There are several different types of warts. The most common warts are those that form on the hand or knee; these are known as verruca vulgaris. They develop as hard bumps on the skin and tend to be pink or brown in color. They can develop as a single entity or in small groups [source: Bupa].
Flat warts are exactly what you think they are: They're flat in shape and can be darker in color or similar to a person's normal skin tone. These warts are more common in women and can be spread to other parts of the body simply by shaving [source: Visual DX Health].
Filiform warts grow on the face around the mouth and nose, while periungual warts develop around the nails and affect their growth [source: WebMD]. Genital warts, on the other hand, are actually considered a sexually transmitted disease (STD). Believe it or not, that isn't the scariest thing about genital warts: what's particularly frightening about them is that you could contract them without your knowledge. Genital warts can look like verruca vulgaris or flat warts, but people who have genital warts often don't have any symptoms at all. Unfortunately, a person with this STD can still pass it on to a partner during sexual intercourse without showing any signs of the disease [source: CDC].
Plantar warts grow on the soles of the feet. Like other warts, they develop as hard bumps, but plantar warts often have black dots in the center due to clotted blood vessels. Plantar warts are often overlooked because they can closely resemble calluses. Occasionally, these warts will grow inward instead of outward, which can cause pain [sources: Skin Care Guide, WebMD].
If you get a wart, you can see a doctor to have it removed, but you may have to make several visits. Most warts will eventually go away without treatment, but this can take up to two years.
Keep reading to find out lots more information on warts.