Computer recycling and disposal refers to the reuse or recycling of used or discarded computers. Computer recycling disposal includes, finding another use for the materials, and dismantling the systems in a way that allows the safe extraction of the reusable materials for reuse in other products. Out of date or obsolete computers are used for computer recycling disposal purposes, as they are a valuable source of secondary materials, however if this process is not carried out in the proper fashion, these computers can be a source of dangerous toxins and carcinogens. Many materials used in the manufacture of computers can be recovered using computer recycling disposal techniques. These materials can include tin, aluminium, iron, silicon and a variety of different plastics. Recovering these materials can reduce the cost of new systems.