A flea market is a type of street market that provides space for vendors to sell previously owned (second-hand) goods. This type of market is often seasonal. However, in recent years there has been the development of 'formal' and 'casual' markets which divides a fixed-style market (formal) with long-term leases and a seasonal-style market with short-term leases. Consistently, there tends to be an emphasis on sustainable consumption whereby items such as used goods, collectibles, antiques and vintage clothing can be purchased, in an effort to combat climate change and fast fashion.

Used goods, also known as secondhand goods, are any item of personal property offered for sale not as new, including metals in any form except coins that are legal tender, but excluding books, magazines, and postage stamps. Used goods may also be handed down, especially among family or close friends, as a hand-me-down.