Many folks want to have a web presence but don't have high-traffic web sites. For these people, providing a dedicated web server may be a waste, because they're paying many hundreds of dollars a month to lease a server that is mostly idle!
Many web hosters offer lower-cost web hosting services by sharing one computer between several customers. This is called shared hosting or virtual hosting. Each web site appears to be hosted by a different server, but they really are hosted on the same physical server. From the end user's perspective, virtually hosted web sites should be indistinguishable from sites hosted on separate dedicated servers.
For cost efficiency, space, and management reasons, a virtual hosting company wants to host tens, hundreds, or thousands of web sites on the same server—but this does not necessarily mean that 1,000 web sites are served from only one PC. Hosters can create banks of replicated servers (called server farms ) and spread the load across the farm of servers. Because each server in the farm is a clone of the others, and hosts many virtual web sites, administration is much easier. (We'll talk more about server farms in Chapter 20.)
When Joe and Mary started their businesses, they might have chosen virtual hosting to save money until their traffic levels made a dedicated server worthwhile (see Figure 18-2).
Figure 18-2. Outsourced virtual ...