What are "classic sunglasses"?

[Igloo]

I have to research this for a class, and I'm having a hard time defining what 'classic' sunglasses are. Does anyone have any picture examples?

[Ignacio]

My personal opinion of "Classic" Sunglasses would be Ray-Ban Wayfarers, shown here by Audrey Hepburn in Breakfast at Tiffany's, Aviator sunglasses by Ray-Ban and Teashades by Ozzy Osbourne.

[Igo]

classic sunglasses usually accepted by lots of people last for a long time. The classic sunglasses styles were designed in the past time. But the sunglasses never out of date and keep popular for many years. For example, aviator style sunglasses are indispensable classic sunglasses. Although the sunglasses style created in World War II, after all these years, they are still popular right now.