A printer is a device that accepts text and graphic output from a computer and transfers the information to paper and usually to standard size sheets of paper. Printers are sometimes sold with computers, but more frequently are purchased separately. Printers vary in size, speed, sophistication, and cost. In general, more expensive printers are used for higher-resolution color printing. Personal computer printers can be distinguished as impact or non-impact printers. Early impact printers worked something like an automatic typewriter, with a key striking an inked impression on paper for each printed character and it strikes the paper a line at a time. The best-known non-impact printers are the inkjet printers. The inkjet sprays ink from an ink cartridge at very close range to the paper as it rolls by. The laser printer uses a laser beam reflected from a mirror to attract ink (called toner) to selected paper areas as sheet rolls over a drum. The four printer qualities of most interest to most users are:

• Color: Color is important for users who need to print pages for presentations or maps and other pages where color is part of the information. Color printers can be set to print only in black-and-white as well. Color printers are more expensive since they use two ink cartridges (one color and one black ink) that need to be replaced after a certain number of pages. Users who don't have a specific need for color and who print a lot of pages will be suggested to find a black-and-white printer that cheaper to operate.
• Resolution: Printer resolution (the sharpness of text and images on paper) is usually measured in dots per inch (dpi). The more dpi that a printer has, the resolution will be higher. Most inexpensive printers provide sufficient resolution for most purposes at 600 dpi.
• Speed: If you do much printing, the speed of the printer becomes important. Inexpensive printers print only about 3 to 6 sheets per minute. Color printing is slower. More expensive printers are operating much faster.
• Memory: Most printers come with a small amount of memory (for example, one megabyte ) that can be expanded by the user. Having more than the minimum amount of memory is helpful and faster when printing out pages with large images or tables with lines around them (which the printer treats as a large image).

Postscript is a printer language that uses English phrases and programmatic constructions to describe the appearance of a printed page to the printer. PCL (Printer Command Language) is an escape code language used to send commands to the printer for printing documents. Escape code language is so-called because the escape key begins the command sequence followed by a series of code numbers. This printer language was developed by Adobe in 1985.