What typically causes the formation of blisters on the skin?

The formation of blisters on the skin is primarily caused by friction between layers of skin. This friction can occur when skin rubs against a surface, such as during physical activity or when using tools, leading to the separation of the epidermis and dermis layers. As this separation occurs, fluid accumulates in the space, resulting in the characteristic raised bubble known as a blister.

While other factors like excessive moisture exposure can also contribute to blister formation, particularly by weakening the skin and making it more susceptible to injury, the direct mechanical action of friction is the key factor that initiates the blistering process. This is why proper footwear and protective measures are important in preventing blisters during activities that require repetitive movements, such as running or hiking.