There are many degrees to which the uneven skin tones can happen, some are most subtle that almost everyone has them and they go unnoticed, and some are severe and they develop. There are many types, some are birthmarks and others are just a result of old age.

Lentigines are dark spots more commonly known as age or liver spot, they often happen due to old age and they are not freckles.

Birthmarks are also another uneven skin tone type and they cannot be prevented, they naturally happen as a result of an abnormal blood vessel in the skin. They can happen anywhere and they are not affected by the sun exposure or over the counter treatments. They can be removed easily with the help of a dermatologist.

Melasma is another uneven skin tone type that often happens with pregnant women, it can also happen hormonally due to some contraceptives or even excess sun exposure.

Seborrheic dermatitis can happen due to irritation or a rash that is not contagious; this rash can develop to become an uneven skin tone discoloration.

Vitiligo are also other skin tone discolorations that happen due to the lack of production in skin hormones and they result in white patches around the body. They can be treated easily as long as you do not leave it to spread around the body.

The other most common types are just due to excessive sun exposure that triggers an irregular amount of melanin which then causes the skin to have an uneven skin tone.