Blisters form when the skin rubs against another surface, causing friction. First, a tear occurs within the upper layers of the skin (the epidermis), forming a space between the layers while leaving the surface intact. Then fluid seeps into the space.
A Blister can be either, a Friction Blister or a Blood Blister.
Friction Blister: A blister occurs when the outer (epidermis) layer of the skin separates from the fiber layer (dermis). The skin will regrow from underneath. The loose skin is dead. Blisters can occur from heat, frostbite, chemical injury, or friction. Unless infection occurs, blisters usually heal quickly.
Blood Blister: A blood blister usually develops following a smashing or pinching injury. There's a small skin injury that pumps blood between the skin layers, raising up a blister of blood. If there are no other signs of a severe injury, blood blisters can usually be treated at home
The hands and feet often rub against shoes, skates, rackets, or other equipment. Blister formation usually requires thick and rather immobile epidermis, as is found in these areas. In addition, blisters form more easily on moist skin than on dry or soaked skin, and warm conditions assist blister formation.
Form as a result of heat, moisture and friction.
Friction forces caused by inappropriate footwear.
Form as a result of fungal infections of the skin, allergic