There are different types of plastics,just as there are different types of metal,paper and glass. Steel and aluminum have to be separated before recycling,different colors of glass must be sorted and white office paper must be separated from newspapers and paperboard boxes. Each of the six common packaging plastics has performance characteristics that make it best suited for specific applications (see "Why do we need different kinds of plastics?"). Purchasers of recycled resins want to be sure that these properties are retained,so handlers sort plastics by resin type to command the highest market value.

Source: ICPE - ENVIS