A garage sale (also known as a yard sale, tag sale, moving sale and by many other names) is an informal event for the sale of used goods by private individuals, in which sellers are not required to obtain business licenses or collect sales tax (though, in some jurisdictions, a permit may be required).

Typically the goods in a garage sale are unwanted items from the household with its owners conducting the sale. The conditions of the goods vary, but they are typically usable. Some of these items are offered for sale because the owner does not want or need the item to minimize their possessions or to raise funds. Popular motivations for a garage sale are for "spring cleaning," moving or earning extra money. The seller's items are displayed to the passers-by or those responding to signs, flyers, classified ads or newspaper ads. In some cases, local television stations will broadcast a sale on a local public channel. The venue at which the sale is conducted is typically a garage; other sales are conducted at a driveway, carport, front yard or inside a house. Some vendors, known as "squatters," will set up in a high-traffic area rather than on their own property.

Items typically sold at garage sales include old clothing, books, toys, household decorations, lawn and garden tools, sports equipment and board games. Larger items like furniture and occasionally home appliances are also sold. Garage sales occur most frequently in rural and suburban areas on weekends with good weather conditions, and usually have designated hours for the sale. Buyers who arrive before the hours of the sale to review the items are known as "early birds" and are often professional restorers or resellers. Such sales also attract people who are searching for bargains or for rare and unusual items. Bargaining, also known as haggling, on prices is routine, and items may or may not have price labels affixed. Some people buy goods from these sales to restore them for resale.

Some jurisdictions require that the home owners obtain a permit (which may require a fee), stating the date(s) on which the sale will take place (with allowances in the event of bad weather conditions). The jurisdiction may also place restrictions on the sale, such as the number of sales in a year a person can have (so as to avoid a person running a business without licenses and without collecting sales taxes), where signs may be placed in and around the neighborhood, and even where on the owner's premises a sale may take place.