A flea market (or swap meet) 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.

Flea market vending is distinguished from street vending in that the market alone, and not any other public attraction, brings in buyers. There are a variety of vendors: some part-time who consider their work at flea markets a hobby due to their possession of an alternative job; full-time vendors who dedicate all their time to their stalls and collection of merchandise and rely solely on the profits made at the market. Vendors require skill in following retro and vintage trends, as well as selecting merchandise which connects with the culture and identity of their customers.

In the United States, the National Association of Flea Markets was established in 1998, which provides various resources for sellers, suppliers and buyers and also provides a means for suppliers and sellers to communicate and form affiliations.