Although most celebrities and some youth like wearing sunglasses, some wear it to protect eyes from sun rays while others do it as a trend.
According to Wikipedia.org, King Nero of ancient Rome wore glasses while watching plays by the slaves.
In China, sunglasses existed in 12th century and were meant for the judges in the court room so as not to scare off witnesses by looking at them in the eyes.
During 1400, judges in Italy wore sunglasses like those in china.
In 18th century, James Ayscough an expert optometrist (eye doctor) from USA made sunglasses but of different colours to help people with vision problems.
According to ideafinder.com, sunglasses meant to protect eyes from sun rays like the existing ones today, were made by Sam Foster in 1029.
Foster could sell his sun glasses to the people going to the beach in Atlantic City. Fosters sunglasses became popular when actors started wearing them to protect their eyes from camera flashlights.
More to that, many people put them on after seeing soldiers of world war 11 wearing them.
Though people with vision disability wear dark sunglasses, there are people who put them on when there is no sunshine.