Apache allows you to create hundreds of virtual host containers. Each container is required to have a ServerName directive, which contains the domain name associated with the virtual host. In addition to a server name, one ore more aliases can be associated with the virtual host with the ServerAlias directive. Aliases can contain a domain, or a regex that allows you to match based on some specific criteria. This is super useful, and allows you to do things like this:
NameVirtualHost 192.168.1.18:8080 <VirtualHost 192.168.1.18:8080> ServerName foo.com ServerAlias *.foo.com </VirtualHost> <VirtualHost 192.168.1.18:8080> ServerName bar.com ServerAlias *.bar.com </VirtualHost>
This opens a whole slew of cool and interesting possibilities for virtual hosting. Niiiiice!