Facsimile machines have come a long way since they were first introduced in the mid-1980s. Today, fax machines are as common an office feature as computers.
Most modern fax machines use a flatbed scanning technology, in which the document moves veritcally using a stepper motor, scanning each line at a time. While early faxes took about 6 minutes to scan page, most fax machines today can accomplish that task in under 10 seconds.
Which size or price range of fax machine you buy will depend primarily on your budget and the number of faxes you send. Faster machines with automatic feeder capabilities will naturally cost more.
For the home office user, a principal consideration will also be phone line use. Smaller faxes that are used infrequently won't need their own phone line, but should come equipped with a splitter that allows it to share your regular phone line.