A wart (also known as verruca) is generally a small, rough tumor, typically on hands and feet but often other locations, that can resemble a cauliflower or a solid blister. 

Cause
Warts are caused by a virus called human papilloma virus or HPV.
• Type 1 is associated with deep plantar (sole of the foot) and palmar (palm of the hand) warts. 
• Type 2 causes common warts, filiform warts, plantar warts, and mosaic plantar warts. 
• Type 3 causes plane warts, commonly known as flat warts. 

Types of wart
• Common wart (Verruca vulgaris), a raised wart with roughened surface, most common on hands and knees; 
• Flat wart (Verruca plana), a small, smooth flattened wart, flesh coloured, which can occur in large numbers; most common on the face, neck, hands,    wrists and knees; 
• Filiform or digitate wart, a thread- or finger-like wart, most common on the face, especially near the eyelids and lips; 
• Plantar wart (verruca, Verruca pedis), a hard sometimes painful lump, often with multiple black specks in the center; usually only found on pressure   points on the soles of the feet; 
• Mosaic wart, a group of tightly clustered plantar-type warts, commonly on the hands or soles of the feet; 
• Genital wart (venereal wart, Condyloma acuminatum, Verruca acuminata), a wart that occurs on the genitalia. 

Treatment
Homeopathy is well known for the treatment of warts maximum cases are reported to have been cured with Thuja , Acid Nit, Caust ect But if it fails selection of constitutional 
drug is necessary which is capable of curing any kind of wart.