The function of a printer is to turn digital data into printed media. This could be text, or it could be graphic output. One of the earliest printers to come with personal computers was the dot matrix printer.
There are two types of printers: impact and non-impact. Impact printers strike the paper with ink to leave behind an impression. Dot matrix printers are an example of printers that impact the paper a line at a time. Non-impact printers create an effect on paper without an impact. An example is the inkjet printer, which sprays ink from a cartridge while the paper rolls by it. Laser printers use lasers to attract ink to paper.
Individual printers can vary in the speed, color, resolution and memory they each have. Resolution on printers is usually measured by dots per inch, or dpi. Users often measure speed in a printer by sheets per minute. Slower printers might do three or four sheets per minute. There are also a variety of different ways of sending data to a printer. The parallel plug interface was a common one. Newer printers use methods such as wireless transmission or a USB port. The newer FireWire technology also often works with printers.