A PC can store information and programs either on diskettes that slip in and out of its disk drives, or on a hard drive inside the system unit, which can hold much more. This also is measured in kilobytes or megabytes. Computer programs are called software . There is probably as much variety in software today as there is in the printed page, from entertainment to reference materials. In addition to the PC itself, you'll need attachments or peripherals .
Individual printers can also serve a group of PCs that are linked together.
Because it involves the use of special hardware, software, and cabling, setting up a network is complex and costly. The process of connecting with other computers or networks outside your own is called on-line communication . The speed at which a modem can send or receive data is measured in bits per second, or bps . Many networks offer educational programming and information. See the Resources section of this Guide for descriptions of some of the services, both commercial and non-profit, that are of interest to educators.