Which skin infection is caused by fungi and results in a reddish circle appearing on the skin?

The skin infection most likely to cause a reddish circle on the skin is ringworm, also known as tinea. Ringworm is a fungal infection that can affect the skin, scalp, and nails. It is caused by a type of fungus called dermatophyte. Ringworm typically appears as a red, circular rash with a raised, scaly border. The rash can be itchy and may spread to other parts of the body.