What is a small bubble on the skin caused by continuous rubbing that fills with serum?

A small bubble on the skin that is filled with serum due to continuous friction is referred to as a blister. Blisters form as a protective mechanism when the outer layers of skin are damaged or irritated, resulting in the accumulation of fluid. This fluid-filled sac helps to cushion and protect the underlying tissue from further injury while it heals.

Warts are caused by a viral infection and have a distinct appearance and texture, while ulcers are open sores often resulting from a variety of conditions, including infections or prolonged pressure. Pimples, on the other hand, are associated with acne and result from clogged pores or inflammation. Each of these skin conditions differs significantly in origin, structure, and function, making the definition of a blister unique and specific to skin irritation and healing processes.