Tinea (pityriasis) versicolor is a chronic fungal (yeast) infection of the skin mainly which is observed in children as well as in adults. This condition is commonly observed in people, especially in tropical and subtropical countries such as India. It tends to stay on for many months or even years, as fungus tends to be resistant to many treatments.

It is caused by the overgrowth of a type of yeast called Malassezia, which is naturally found on the skin. Under certain conditions, this yeast can multiply excessively and lead to the development of tinea versicolor. The initiation of this condition is influenced by various factors, including:

1) Malassezia Yeast: The fungus Malassezia is a normal part of the skin flora. However, in some individuals, it can overgrow and disrupt the normal balance of microorganisms on the skin.

2) Warm and Humid Conditions: Malassezia thrives in warm and humid environments. Tinea versicolor is more common in regions with hot and humid climates.

3) Oily Skin: The yeast feeds on the oils produced by the skin's sebaceous glands. Individuals with oily skin may be more prone to tinea versicolor.

4) Hormonal Changes: Hormonal fluctuations, such as those that occur during adolescence, pregnancy, or while taking oral contraceptives, can increase the risk of developing tinea versicolor.