Raised pocket of fluid (usually clear) covered by skin
Friction Blister:
friction blisters usually occur on the palms, fingers, heels or toes.
Blood Blister:
raised pocket of bloody fluid, covered by skin. Dark red or purple in color. A blood blister can occur when the skin gets pinched (in a hinge or a closing door).
Blisters when the cause is unknown are also covered.
