Warts are usually referred to as common warts or in latin, verruca. A general description of common warts is that they are localised growths in the skin, caused by an infection of the human papillomavirus, also known as HPV. There are more than 100 types of HPV and the effect of this virus will vary from type to type. Some of the HPV types will cause common warts on the skin, while others infect other areas of the body, such as the genitals. Warts are regarded as contagious, but they are not seen as a high risk of infection. For example, if one family member gets infected and has a wart, the rest of the family does not get infected. The probability of getting an HPV-infection and grow warts depends on the immune system. Some people have a strong defence against the virus and will almost never get infected, while others will catch this virus more readily.

Warts generally affects only one part of the body, most often the hands and feet get infected, but in some rare cases they can spread to other body parts by touch and in that way the HPV is spread. Warts generally causes no tenderness or pain but there are exceptions, such as large plantar warts on the heel.

Common types of warts
The most frequent type of warts is the common wart. This type of warts has a dome-shaped appearance and is most often found on fingers, toes and knees. This type of warts tends to appear more often in children younger than teenagers.

Plantar warts. These appear under the foot and are often flat. This type of warts can be tender or cause pain. This is the most common type of warts on the feet and it has a tendency of appearing in teenagers. This type of warts are more difficult to treat than common warts.
Flat or non-protruding warts. These occur on the face, legs and other parts of the body, often in a significant number.
Periungual warts. These are warts around or under the nail.
Filiform warts. This variant of warts are often flat and protrude like a stalk, most commonly found on the face.

To remove warts
The following information on how to remove warts is general, and mainly applies to remove common warts, and it does not apply to removing genital warts. Common warts can be experienced as vastly irritating. Generally, fifty percent of all warts heal by themselves within 18 months in persons with a normal health status, but can also remain for several years. Treating warts requires a lot of patience. Warts can appear and disappear without any defined causes, or have causes that are hard to identify. There are a variety of different treatments and a vast array of types of warts. Some warts will spread, while others will not. All in all, warts are rarely tender or painful. If they are causing pain they are most often situated on a part of the body where they are subject to pressure or friction, such as the sole of the foot or the palm of the hand.

Wart treatments may give a varied result. Some warts will respond to treatment whilst others will not, even if the treatment is done on the same person and on the same type of warts. Wart treatment often requires several repetitions over weeks, months and, in extreme cases, years to succeed. Warts are removed by treatments that may be done at home, in health clinics or at a dermatologist. Wart treatments at a dermatologist is often more expensive compared to home treatments. Home treatments come in different variants. The most common variants are ointments, gel or plasters.

Salicylic acid based treatments
This kind of treatment against wart viruses comes as drops, gels and plasters. They are intended for application on all types of warts, from small warts to large lumps. Salicylic acid is a keratolytic treatment which means that it dissolves the protein (keratin) that make up the wart and the layer of dead skin cells often surrounding it. It can therefore be said that this type of treatment corrodes the wart.

Non-prescription cryotherapy
Treatments based on aerosol bought over the counter, applies a freezing spray which freezes warts at a temperature of −70 F (−57 C). This type of treatment can be compared to liquid nitrogen, which is used by most dermatologists. Liquid nitrogen is significantly colder (−320 F or −196 C). Cryotherapy destroys the wart’s tissue during the freezing and the dead tissue falls off.

Duct tape
Allegedly, warts can be “suffocated” by covering them up with duct tape or other airtight tapes, such as electrical tape. This variety of treatment does require that the tape is covering the area at all times and should only be off for a few hours each week. The tape will almost always fall off, and must be changed often. The effect of this treatment is somewhat unclear, and it cannot be established that the treatment is actually helpful.

Surgery for removing warts
There are several different surgical approaches to remove warts.

Is one of the most common interventions, and it is based on freezing the wart’s tissue and destroy it. To remove a wart completely, three sessions might be necessary.

is a type of treatment taking effect through destroying the wart’s tissue by an electric current. Electrodesiccation can result in scarrs.

Laser surgery
as treatment for warts is normally used as a last resort as it is rather expensive and painful. Laser surgery may be necessary to treat large warts not responding well to other treatments.

or, in other words, burning/(burning of) is an effective treatment. The patient is anaesthetized and the wart is burned away. This method is effective but may cause scarring.