The word printer means different things in different fields of applications. Going by the generic meaning, a printer means one who is in the occupation of printing and publishing. It also means a device which prints out the results of data computed by computers, as applied to computers. In the celluloid world, it stands for devices used to copy and modify photos.

Computer printer transforms digitally stored documents of graphics or text data into paper/hard copies. Printers can be permanently interfaced with individual computers or can be anywhere in the network, invariably through network interfaces, either wired or wireless, so that any or all users can share for hard copy production. You will normally see a wired network in small areas known as LAN and wireless networks or Ethernets are over a wide area (WAN).
Modern Printers have evolved so much that you can have true life quality printing with them which is a departure from the earlier 'dot matrix' printers. Printers like Inkjet, Laser printers, Plotters, Thermal printers, Digital minilabsare relevant today.

Generally in an office environment, the first three types of printers are the preferred ones. These are designed especially for office needs such as printing text matters, graphics like charts and power point presentation documents etc with an exception that plotters are dedicated for uses like constructional drawings which can't be 'printed'.
Inkjet printers print by placing extremely small (50-60 microns in size) ink drops precisely in the format of the original document. The precision is so high that equals resolutions of 1440x720 dpi. The dots can any colors in predetermined combination to create color images.Laser printers work similar to photocopiers but differing in producing images. The document is directly scanned on to a photosensitive drum creating a negative image which is later developed by 'lamping back' and pressurized rolling over the paper by fusing.Plotters can print only line diagrams by one or more pens moving laterally according to the commands received by them.