Some websites have variable prefixes. For example: www.example.com/bob_11 is presented as bob_11.example.com. How do I do that? I assume its a sub-directory, but can't find anything explaining how to treat it as such.
I recently set up an apache server, if the specific server software is a factor. The closest I've found is mod_rewrite, but it clearly doesn't do what I want.
Searching for help on this issue has been tricky, as I'm pretty sure "prefix" is the wrong word for what I'm describing. Aside from how to do it, what's the word for the process I'm describing?