Vintage clothing is a generic term for garments originating from a past era. According to Wikipedia, it has been part of the world since World War I as an effort to reuse clothing to manage the textile shortage.
The term "Vintage" is often used to refer to older styles of clothing and accessoriees. A generally accepted industry standard consider items made between 20 -100 years ago to be "vintage". Some may also consider if the clothing clearly reflects styles and trends of the era they represent, but for most people this is secondary.
"Retro- or Vintage style" usually refers to imitating typical ways of styling clothes of previous eras and does not necessarily consist of clothing pieces older than 20 years.
Where to find it
There are loads of places to find vintage clothing and accessories, online as well as offline. I have listed a selection of my favorite sites for online vintage shopping, most of them also offer second hand pieces, less than 20 years old.
Click the links to learn more about each site, get buying guides, or get straight to exploring their massive supply of goods.