Monochrome laser printers are machines that print text and images from computers by using a laser beam to control where a single color is applied to paper. They're often faster than other types of printers and can generally produce large numbers of black-and-white documents cheaper than other printers.
What Monochrome Means
The term monochrome refers to any technology that produces output in a single color. Early computer monitors that displayed white or green text on a black background are categorized as monochrome and so are printers that only print with black ink.
How to Print With a Laser
All printers need to take images sent by a computer and translate them into ink on paper. Different types printers do this in different ways.
A laser printer has a processor chip that takes the image it receives from the computer and translates it into a black-and-white grid of pixels -- dots that will be printed onto the paper.
The printer has a rotating cylindrical part called a drum that's given a static electric charge. The drum has a special that's sensitive to light, so tiny areas of the drum that are exposed to light lose their charge.
A laser inside the printer zaps the rotating drum with a beam, removing parts of its charge so that the bits that stay charged correspond to the pixels being printed onto the page. The drum is then exposed to toner, a mix of black-colored carbon particles and plastic, which sticks to the charged parts of the drum thanks to static electricity.
The drum rolls across a sheet of paper, transferring the toner to the paper in the same grid that was zapped into the drum. The paper passes through a fuser -- a set of rollers that melts the toner onto the page and presses it firmly into place, making the image permanent.
When to Use a Monochrome Laser Printer
Because monochrome laser printers only print in black, they're not suitable for printing color photos or anything else that requires color.
They're often more expensive to buy than the color inkjet printers often used for home printing, and the toner cartridges they use can be more expensive than the ink cartridges used in inkjet printers.
But each toner cartridge prints significantly more pages than an inkjet cartridge, making them cheaper in the long run if you print thousands of pages a year.
Monochrome laser printers are usually faster than inkjet printers, which is an advantage in busy offices.