A toner cartridge is a consumable element of a laser printer. The toner within the cartridge is like ink, except that it consists of a mixture of plastic particles, carbon and colours. These combined together create the image.The toner itself is transferred to the paper by using a photo receptor drum unit. The toner mixture clings to the heated rollers within the drum and are fused onto the paper. Printers have either a cartridge/drum combined unit or separate components. Toner cartridges are similar to inkjet cartridges which are used in inkjet printers.Printer toner cartridges can vary in longevity, however, low to mid-range laser printers contain a drum unit which has a typical life span of 40,000 pages, and toner cartridge which has a typical life span of 2,000 pages.Toner cartridges can sometimes be expensive so toner refill kits are available giving the user the option of refilling the empty cartridge.If a laser printer has a chipped cartridge installed the smart chip recognises when the toner is low and sends this information to the printer. If the cartridge is being refilled the chip needs to be reset using a simple plastic tool called a re-setter.Toner cartridges can be recycled, with some stores offering a recycling facility where you can earn rewards. Toner and Ink cartridges can be refilled two to three times creating less waste. Toner cartridges which are not empty could be considered as hazardous waste and need to be disposed of correctly.Original equipment manufacturer (OEM) cartridges are supplied by the manufacturers and offer guarantees as to the quality of the toner and drum.Compatible cartridges are manufactured by third party printer cartridge companies and sold under other brand names. They quite often vary in their design from the OEM cartridges but have been designed to be a compatible equivalent. These include brands such as, Epson, Lexmark, Samsung, Pantum and HP LaserJet.