Sunglasses are a special kind of glasses that have been specially darkened to stop bright light from hurting your eyes. When you wear them, the world seems to become a little less bright, which can be a relief on very sunny days. They go all the way back to Roman times, and are especially popular today in the summer and on beaches.
However, shielding their eyes from light is not the only reason that people wear sunglasses. They can also sometimes look good in themselves as a fashion accessory, and people may also use them to hide their eyes from others when they are upset, or on drugs, or don't want people to see their eyes for some other reason celebrities who don't want their photo taken, for example. People with missing eyes or who are blind often wear sunglasses in preference to things like eyepatches.
One word of warning: many people will react badly towards you if you wear sunglasses indoors for no apparent reason, thinking that you are just doing it because you want to make a fashion statement. It can also be dangerous to wear sunglasses in places that aren't very bright, as you won't be able to properly see where you're going and may trip over or walk into things.
There are also medical reasons to wear sunglasses, particularly the fact that protecting your eyes from the sunís ultraviolet rays can reduce the risk of eye cancer, as well as some eye conditions like cataracts. It is possible to get prescription sunglasses that correct vision like normal glasses while protecting their wearer from the sun at the same time, although these can be expensive.
When you buy a pair of sunglasses, do make sure to check that they offer 100% protection against the sun's UV rays, as not all the cheaper models do. Because the sunglasses cause your pupils to widen as they do in the dark, cheap sunglasses can cause huge amounts of UV radiation to enter your eyes, therefore doing much more harm than good.