Walking around barefoot in your house, going on long runs, wearing shoes that are too tight or too loose – all of these can create friction on the skin that may lead to calluses.

These thick, rough patches are your skin’s natural defence against chafing and irritation, said Dr Sari Priesand, a podiatrist at University of Michigan Health. “The skin thickens in response,” she added, creating a tough layer that guards against further damage.

Calluses can crop up year-round, she said, but you may notice them more during warmer months, when walking around barefoot or wearing less supportive shoes such as flip-flops. People are generally more active in the summer too, she added.

Calluses are not always something to worry about. But if they get too thick, they can become painful or even crack, leaving your skin vulnerable to infection. And some find them unsightly.

The good news, experts said, is that removing and preventing calluses is fairly straightforward.

Calluses can form on any part of the body that regularly encounters pressure or friction, said Dr Jacob Beer, a dermatologist in West Palm Beach, Florida. These include the balls of the feet, the heels and the bottoms and sides of toes.

They are also common on hands: Golfers, weightlifters and gymnasts get calluses frequently. People who have irregularly shaped feet or toes – such as those with bunions, hammertoes or flat feet – also get them often.

Calluses appear as yellowish or whitish thickened areas of skin that feel rough, said Dr Chang Son, a dermatologist in New York City.

They are usually painless, but can become tender and uncomfortable under pressure, he added. Sometimes, this may cause you to walk unevenly.

Calluses are often confused with corns, Dr Son said.

While they are both hardened areas of skin that form as a defence against friction, corns are usually smaller, rounder, more painful and have deep, hard centres, Dr Priesand said. Ca...