When your copier is indicating "toner low," it's time get more. Depending on the type of copier you have, the way this is done will be different. There are three different ways this is done:
Refilling the toner in the copier itself
Most copiers require copier toner refills. The refills come in plastic bottle containers, and the contents are poured into a designated toner container on your copy machine.
Replacing the toner cartridge
Toner cartridges are typically used in lower-end photocopiers They're more expensive than the bottle refills, but you have the option of purchasing compatible or remanufactured cartridges, which saves you money.
Refilling the manufacturer's cartridges.
Lastly, many manufacturers, like Xerox, have cartridges that are refillable. With these, you don't need to buy new cartridges. Instead, you purchase toner cartridge refill bottles to refill them yourselves.