Scrap consists of recyclable materials, usually metals, left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap can have monetary value, especially recovered metals, and non-metallic materials are also recovered for recycling. Once collected, the materials are sorted into types – typically metal scrap will be crushed, shredded, and sorted using mechanical processes.

Metal recycling, especially of structural steel, ships, used manufactured goods, such as vehicles and white goods, is an industrial activity with complex networks of wrecking yards, sorting facilities, and recycling plants. The industry includes both formal organizations and a wide range of informal roles such as waste pickers who help sorting through scrap.

Scrap metal originates both in business and residential environments. Typically a "scrapper" will advertise their services to conveniently remove scrap metal for people who don't need it.

Scrap is often taken to a wrecking yard (also known as a scrapyard, junkyard, or breaker's yard), where it is processed for later melting into new products. A wrecking yard, depending on its location, may allow customers to browse their lot and purchase items before they are sent to the smelters, although many scrap yards that deal in large quantities of scrap usually do not, often selling entire units such as engines or machinery by weight with no regard to their functional status. Customers are typically required to supply all of their own tools and labor to extract parts, and some scrapyards may first require waiving liability for personal injury before entering. Many scrapyards also sell bulk metals (stainless steel, etc.) by weight, often at prices substantially below the retail purchasing costs of similar pieces.

A scrap metal shredder is often used to recycle items containing a variety of other materials in combination with steel. Examples are automobiles and white goods such as refrigerators, stoves, clothes washers, etc. These items are labor-intensive to manually sort things like plastic, copper, aluminum, and brass. By shredding it into relatively small pieces, the steel can easily be separated out magnetically. The non-ferrous waste stream requires other techniques to sort.

In contrast to wrecking yards, scrapyards typically sell everything by weight, instead of by item. To the scrapyard, the primary value of the scrap is what the smelter will give them for it, rather than the value of whatever shape the metal may be in. An auto wrecker, on the other hand, would price exactly the same scrap based on what the item does, regardless of what it weighs. Typically, if a wrecker cannot sell something above the value of the metal in it, they would then take it to the scrapyard and sell it by weight. Equipment containing parts of various metals can often be purchased at a price below that of either of the metals, due to saving the scrapyard the labor of separating the metals before shipping them to be recycled.

Thieves sometimes sell stolen items to scrapyards. Copper pipes and wiring, bronze monuments and aluminium siding have all been targets of metal theft, with the number of thefts increasing as prices rise. Manhole covers have also been stolen. In the 1970s, the term "newsjacking" was coined to describe the theft of newspapers for sale to scrap dealers.

Scrap prices may vary markedly over time and in different locations. Prices are often negotiated between buyers and sellers directly or indirectly over the Internet. Prices displayed as the market prices are not the prices that recyclers will see at the scrap yards. Other prices are ranges or older and not updated frequently. Some scrap yards' websites have updated scrap prices.