A sub domain is different from Addon domain or Domain Alias.
A sub domain is a name before your main domain, e.g. http://blog.domain.com
There are various benefits and reasons for creating Sub domains, like:
- There are easier to remember. For example, http://blog.chromeis.com might be easier to remember then http://chromeis.com/blog
- You can control technologies for subdomain independent of main domain. For example, domain.com might have PHP4 enabled on all directories, but blog.domain.com might have PHP5 on it.
- It is easier to backup and restore your domain and sub domains separately – instead of piling everything under main domain/directory.
