There are several ways of hosting multiple websites in a single server. However, using virtual hosts is the simplest with the least overhead. As Apache stands to be the industry standard how to setup virtual hosts using Apache.software, Linux-tips.net gives us a tutorial in
Personally, however, I prefer having one site hosted in one web server. If you are short in servers, then you can use virtualization solutions. Solaris has Containers and Zones for this and Linux has Xen. It should not be that difficult.