There are different styles of sunglasses, some of them are classified by their shape or looks, some of them are named by their frame design.
In details, they are Aviator sunglasses, Wayfarers sunglasses, Wrap-around sunglasses sunglasses, Round/Square/Oval sunglasses according to their shape.
Besides, according to their designs, there are Clip-on glasses, Flip-up sunglasses, Mirrored sunglasses and Gradient lenses sunglasses etc.
There are so many different styles of sunglasses. I just recommend you some of them. One of them is aviator sunglasses which are always in fashion these years and are popular with both men and women. Another one of them is mirrored sunglasses which become popular these days. Mirrored sunglasses can help hide eyes so that other people cannot see their eyes directly. And there are polarized sunglasses and oversized sunglasses which have become popular for many years and they are still in fashion now.
There are two main types of sunglasses for protecting eyes based on its usage. One is the normal sunglasses, which is decoration in people's daily life. The other one is UV polarizing glasses, which is usually used in some works. E.g. pilots need wear sunglasses for protecting eyes and keeping safety that is called Aviator sunglasses.