Warts are caused by a virus. If they are genital then its really virulent and you have to go to doctor. Otherwise there are treatments you can use. There is loads of advice online, weirdest I saw was duct tape! Apparently its a serious one and quite a bit of research has been done. The theory is that the skin recognises the foreign body and sends white blood cells to the area which whilst there, attack the wart virus; its reckoned to be more effective than freezing it off as a doctor might. Otherwise verruca cream can be used or there is the old wives tail about rubbing it with steak and then burying the steak in the garden!! Remember to wash your hands well whatever you do as it can spread.