what is the meaning of tanning on skin
Sun tanning By the early 20th century, the therapeutic benefits of sunlight began to be recognised.[26] In 1903, Niels Finsen was awarded the Nobel Prize in Medicine for his “Finsen Light Therapy”.[27] The therapy was a cure for diseases such as lupus vulgaris and rickets. Vitamin D deficiency was found to be a cause of rickets, and exposure to the sun would allow vitamin D to be produced in a person. Therefore, sun exposure was a remedy to curing several diseases, especially rickets. In 1910 a scientific expedition went to the island of Tenerife to test the wider health benefits of "heliotherapy",[28] and by 1913 "sunbathing" was referred to as a desirable activity for the leisured class.[29]
Skin immunity Skin immunity is a property of skin that allows it to resist infections from pathogens. In addition to providing a passive physical barrier against infection, the skin also contains elements of the innate and adaptive immune systems which allows it to actively fight infections. Hence the skin provides defense in depth against will infection.