Money saving tips and information:

A toner cartridge, also called laser toner, is the consumable component of a laser printer. Toner cartridges contain toner powder, a fine, dry mixture of plastic particles, carbon, and black or other coloring agents that make the actual image on the paper. The toner is transferred to paper via an electrostatically charged drum unit, and fused onto the paper by heated rollers during the printing process.

Variants:
Low-end to Mid-range Laser Printers typically contain two consumables parts: the toner cartridge itself (typical life 2,000 pages) and the Drum Unit (typical life 40,000 pages). Some toner cartridges incorporate the Drum Unit in the design and therefore replacing the toner means replacing the drum unit every single time, although some consider this type unessential and therefore not cost-effective.