There are a couple of options available for hosting your site.

Shared Server

Here you rent space on a server. Your site is separate but on the same physical hardware as other sites that also rent space on the server. This has the advantage of keeping costs down although ultimately you do not have total control of all the server settings. The server provider takes care of all security issues and provides backup services including duplicate servers in case of hardware failure.
This is the option I offer if I host your site for you.

Dedicated Server

Alternatively you can buy your own server and have full control over the configuration.
There is however a cost to this an in addition there are significant security issues to be aware of and you will need to have backup systems and servers in place in case of hardware failure.