Warts are viruses which enter through the skin. Some people are more susceptible to warts for reasons that are not completely clear, but likely have to do with immune function and skin integrity. If you do nothing, the body’s immune system will eventually get rid of warts, but it may take months to years, and the warts may multiply/spread in the meantime.
Getting rid of warts is not always easy, and no single method works better than another for any particular patient. Treatments are segregated into destructive methods and those that stimulate the immune system.