The ancient Greeks used olive oil as a type of sunscreen. However, this was not very effective. Throughout the early twentieth century, H.A. Milton Blake, a South Australian chemist, as well as several other inventors attempted to create an effective sunscreen but failed.
It was not until 1944 that the first effective sunscreen was invented. At that time, World War II was in full swing and many soldiers were getting serious sunburn. A pharmacist named Benjamin Greene decided to create something that would save the soldiers from the sun’s harmful rays. In his wife’s oven, he created a sticky, red substance which he called "red vet pet" (red veterinary petrolatum), which worked primarily by physically blocking the sun's rays with a thick petroleum-based product similar to Vaseline. Greene tested it on his own bald head. It did not work nearly as well as modern sunscreens, but it was a start.
Sunscreen has come a long way since its initial days. Modern products have much higher protection factors than Greene's sunscreen, and modern products can also be water- and sweat-resistant. But there are also negative effects. Some people rely too much on the product and do not understand the limitations of the sun protection factor (SPF); they assume that buying anything over SPF 30 will automatically prevent them getting burnt no matter how long they can stay in the sun. Too much sunbathing is one of the major causes of skin cancer across the world.
Addendum: An effective sunscreen had already been developed in 1938 by the Swiss chemistry student Franz Greiter, after he had severely burnt himself during an ascent of the Piz Buin on the border between Switzerland and Austria. He named his product, which he had developed in a small laboratory in his parents' home, Gletscher Creme or in English Glacier Cream. Still existing examples of the 'Glacier Cream' have shown to have a SPF of 2 and thus could be classed as an effective sunscreen.
