From Sunshine to Sunless Tanning
Sun tanning is the process by which skin pigmentation is darkened or tanned. It is most often a result of exposure to ultraviolet radiation from sunlight or from artificial sources such as a tanning lamp found in indoor tanning beds. People also use sunless tanning products which can produce the tanning effect of darkening the skin without exposure to ultraviolet radiation.
The most-common risk of exposure to ultraviolet radiation is sunburn. Overexposure to ultraviolet radiation is known to cause skin cancer,  cause skin age and wrinkle faster, mutate DNA, and impair the immune system. Frequent tanning bed use triples the risk of developing melanoma, the deadliest form of skin cancer, according to a 2010 study.  The study suggests that the melanoma risk is linked more closely to total exposure than it is to the age at which an individual first uses a tanning bed. The International Agency for Research on Cancer places the use of tanning beds in the highest cancer risk category.
Several organizations, such as the World Health Organization, the American Cancer Society and the US Surgeon General have issued guidelines warning about sun tanning and UV radiation exposure, either from the sun or from indoor tanning. 
To avoid exposure to UVB and UVA rays, people take alternative steps to appear with darkened skin. They use sunless tanners also known as self-tanners, spray tans and airbrush tanning. Sunless tanners contain the ingredient dihydroxyacetone (DHA), cosmetic bronzers and a variety of plant and fruit extracts which help repair, rejuvenate, and protect the skin. Benefits of sunless tanning include instant results and the ability for the user to maintain complete control of how light or dark they choose their skin to become, all without the damaging effect of the sun.
Many sunless tanning products are available including darkening creams, gels, and lotions, all of which are self-applied on the skin. There is also a professional spray-on tanning option that is offered by spas, salons, and tanning businesses. Spray tanning involves a cosmetic bronzer being sprayed on the body while DHA reacts with proteins in the top layer of the skin, resulting in a brown tanning color.
GIA released a comprehensive global report on the Sunless Tanning markets in 2014. The world market for sunless tanners is projected to reach $1 billion by the year 2018. Increasing awareness among the consumers about the damage and health risks caused by ultraviolet radiation sun exposure, and product innovations are driving the market growth globally. The sunless tanning market shows no signs of slowing down due to the increase taxation and regulations on tanning beds and in some countries a complete ban of tanning beds altogether. (i.e. Brazil and Australia)
^ "Reviewed Substances". ntp.niehs.nih.gov. Retrieved 13 December 2016.
^ Peeples, Lynne. Study: Frequent tanning-bed use triples melanoma risk. CNN. 27 May 2010
^ "Skin Cancer". www.cancer.org. Retrieved 9 February 2017.
^ General, Office of the Surgeon. "The Surgeon General’s Call to Action to Prevent Skin Cancer". www.surgeongeneral.gov. Retrieved 9 February 2017.