Recyclable materials include many kinds of glass, paper, metal, plastics, textiles, and electronics (e.g., cell phones and computers). Although similar in effect, the composting or other reuse of biodegradable waste – such as food or garden waste – is not typically considered recycling. Materials to be recycled are either brought to a collection center or picked up from the curbside, then sorted, cleaned, and reprocessed into new materials bound for manufacturing.

In a strict sense, recycling of a material would produce a fresh supply of the same material, for example used office paper to more office paper, or used foamed polystyrene to more polystyrene. However, this is often difficult or too expensive (compared with producing the same product from raw matrials or other sources), so "recycling" of many products or materials involves their reuse in producing different materials (e.g., cardboard) instead. Another form of recycling is the salvage of certain materials from complex products, either due to their intrinsic value (e.g., lead from car batteries, or gold from computer components), or due to their hazardous nature (e.g., removal and reuse of mercury from various items).

Critics of recycling claim that it often wastes more resources than it saves, especially in cases where it is mandated by government. Note here that municipal recycling may nevertheless still be worthwhile if the net cost is less than the landfill or other disposal costs for the same amount of material.

Background

In the United States, recycling facilities earn estimated revenues of $2,981 million a year. Growth has exceeded 7% per year for the past five years (from 2003 to 2008) due to rising waste volumes and increasing recyclable commodity prices. New initiatives can change the industry. For example, in California and New York, moves to raise the requirements for the set amount of waste to be diverted from the waste stream from 50 percent to 75 percent can produce healthy profits for companies that collect and process recyclables.

There is some debate over whether recycling is economically efficient. Municipalities often see fiscal benefits from implementing recycling programs, largely due to the reduced landfill costs. A study conducted by the Technical University of Denmark found that in 83% of cases, recycling is the most efficient method to dispose of household waste. In addition to fiscal benefits, justification for recycling lies in what economists call externalities, unpriced costs and benefits which accrue to individuals outside of private transactions. Examples include: increased air pollution and greenhouse gases from incineration, reduced hazardous waste leaching from landfills, reduced energy consumption, and reduced waste and resource consumption, which leads to a reduction in environmentally damaging mining and timber activity. Without mechanisms such as taxes or subsidies to internalize externalities, businesses will ignore them despite the costs imposed on society. In order to make such non-fiscal benefits economically relevant, advocates have pushed for legislative action to increase the demand for recycled materials. The United States Environmental Protection Agency (EPA) has concluded in favour of recycling, saying that recycling efforts reduced the country's carbon emissions by a net 49 million metric tonnes in 2005. In the United Kingdom, the Waste and Resources Action Programme stated that Great Britain's recycling efforts reduce CO₂ emissions by 10-15 million tonnes a year. Recycling is more efficient in densely populated areas, as there are economies of scale involved.