4.Aviators
Aviators are sunglasses with an oversized teardrop-shaped lens and thin metal frames. This design first appeared in 1936 by Ray Ban for issue to U.S. military aviators. Their popularity with pilots, military and law enforcement personnel in the United States has never wavered. As a fashion statement, models of aviator sunglasses are often made in mirrored, colored, degregated, and wrap-around styles. In addition to pilots, Aviator-style sunglasses gained popularity with young people in the late 1960s and continued to be very popular through the ’70s and early ’80s.

5.Wayfarers
First introduced by Ray-Ban, the Wayfarer design popularized since the 1950s by Hollywood celebrities such as James Dean is thought to be the bestselling sunglasses design to date

6.Teashades
‘Teashades’ (sometimes also called ‘”John Lennon glasses” or “Ozzy Glasses”, after Ozzy Osbourne’) were a type of Psychedelic art wire-rim sunglasses that were often worn, usually for purely aesthetic reasons, by members of the 1960’s drug counterculture, as well as by opponents of segregation. Rockstars such as Mick Jagger, John Lennon, Jerry Garcia, Ozzy Osbourne, and Janis Joplin all wore teashades. The original teashade design was made up of medium-sized, perfectly round lenses, supported by pads on the bridge of the nose and a thin wire frame. When teashades became popular in the late 1960s, they were often elaborated; lenses were elaborately colored, mirrored, and degregated, and often of excessively large size, and the wire earpieces were sometimes exaggerated. A uniquely-colored or darkened glass lens was usually preferred
The term has now fallen into disuse, although references can still be found in literature of the time. Teashades are briefly referenced during a police training seminar in Hunter S. Thompson’s Fear and Loathing in Las Vegas. ‘Teashades’ also was used to describe glasses worn to hide the effects of marijuana (conjunctival injection) or ‘bloodshot’ eyes or the effects of opiates such as heroin (pupillary constriction).

7.Glacier Glasses
Sunglasses with round lenses and leather blinders that protect the eyes by blocking the sun’s rays around the edges of the lenses. Because they provide extra protection from bright sun and light reflected by snow and ice, they are often used when traveling across glaciers or snowfields

James Ayscough began experimenting with tinted lenses in spectacles in the mid-18th century. These were not “sunglasses” as such; Ayscough believed blue- or green-tinted glass could correct for specific vision impairments. Protection from the sun’s rays was not a concern of his.

Yellow/Amber and brown-tinted spectacles were also a commonly-prescribed item for people with syphilis in the 19th and early 20th centuries because of the sensitivity to light that was one of the symptoms of the disease.

2.Modern developments
In the early 1900s, the use of sunglasses started to become more widespread, especially among the pioneering stars of silent movies. It is commonly believed that this was to avoid recognition by fans, but the real reason was they often had perennially sore eyes from the powerful arc lights that were needed due to the extremely slow speed film stocks used. The stereotype persisted long after improvements in film quality and the introduction of ultraviolet filters had eliminated this problem. Inexpensive mass-produced sunglasses were introduced to America by Sam Foster in 1929. Foster found a ready market on the beaches of Atlantic City, New Jersey, where he began selling sunglasses under the name Foster Grant from a Woolworth on the Boardwalk.

Sunglasses first became polarized in 1936, when Edwin H. Land began experimenting with making lenses with his patented Polaroid filter.

In 2004, Oakley developed the THUMP, sunglasses with built-in digital audio player. This design has been copied by a number of smaller companies.

Other names of sunglasses

There are also various words referring to eyepieces with darkened lenses:
.Glares is a term popular in India if the glass is dark. If it is light then Coolers
.Sun spectacles is a term used by some opticians.
.Spekkies is a term used predominantly in southern Australia.
.Sun specs (also sunspecs) is the shortened form of the above term.
.Sunglasses is a term in common usage in Britain and North America, and it is also used when preceded by “pair of”.
.Sun-shades can also refer to the sun-shading eyepiece-type, although the term is not exclusive to these. Also in use is the .derivative abbreviation, shades.
.Dark glasses (also preceded by pair of) - generic term in common usage.
.Sunnies is Australian and New Zealand Slang
.Specs is a common name for sunglasses in North America.
.Smoked spectacles usually refers to the darkened eyepieces worn by blind people.
.Solar Shields Usually refers to the models of sunglasses with large lenses.
.Stunna shades Used as a slang term in the hyphy movement, usually referring to sunglasses with oversized lenses.
.Shades
.Hater blockers
.Locs (also maddoggers) is a term for very dark lensed sunglasses.
Cheaters
.Sang Gleezies (from sunglasses)
.Eyewear is a term used by opticians

Any of the above features: color, polarization, gradation, mirroring, and materials can be combined into the lens for a pair of sunglasses. Gradated glasses are darker at the top of the lens where the sky is viewed and transparent at the bottom.
Corrective lenses or glasses can be manufactured with either tinting or darkened to serve as sunglasses. An alternative is to use the corrective glasses with a secondary lenses such as oversize sunglasses that fit over the regular glasses, clip-on lens that are placed in front of the glasses, and flip-up glasses which feature a dark lens that can be flipped up when not in use. Photochromic lens gradually darken in bright light

(2).Frames
Frames are generally made from plastic, nylon, a metal or metal alloy. Nylon frames are usually used in sports because they are light weight and flexible. They are able to bend slightly and return to their original shape instead of breaking when pressure is applied to them. This flex can also help the glasses grip better on the wearer’s face. Metal frames are usually more rigid than nylon frames thus they can be more easily damaged when participating in sporty activities, but this is not to say that they cannot be used for such activities. Because metal frames are more rigid, some models have spring loaded hinges to help them grip the wearer’s face better. The end of the ear pieces and the bridge over the nose can be textured or have a rubber or plastic material to hold better. The end of the ear pieces are usually curved so that they wrap around the ear; however, some models have straight ear pieces. Oakley, for example, has straight ear pieces on all their glasses

Frames can be made to hold the lenses in several different ways. There are three common styles: full frame, half frame, and frameless. Full frame glasses have the frame go all around the lenses. Half frames go around only half the lens, typically the frames attach to the top of the lenses and on the side near the top. Frameless glasses have no frame around the lenses and the ear stems are attached directly to the lenses. There are two styles of frameless glasses: those that have a piece of frame material connecting the two lenses together, and those that are a single lens with ear stems on each side

Some sports-oriented sunglasses have interchangeable lens options. Lenses can be easily removed and swapped with a different lens, usually a different colored lens. The purpose of this is to allow the wearer to easily change lenses when light conditions or activities change. The reason for this is because the cost of a set of lenses is less than the cost of a separate pair of glasses and carrying extra lenses is less bulky than carrying multiple pairs of glasses. It also allows easy replacement of a set of lenses if they are damaged. The most common type of sunglasses with interchangeable lenses have a single lens or shield that covers both eyes. Styles that use two lenses also exist, but are less common.

(3).Nose Bridge
Nose bridges allow support between the lens and the face. Nose bridges also prevent pressure marks caused by the weight of the lens or frame on the cheeks. People with large noses may need a low nose bridge on their sunglasses. People with medium noses may need a low or medium nose bridge. People with small noses may need sunglasses with high nose bridges to allow clearance.