Apache , virtualhost

Host websites on your local machine using Apache websever
VirtualHost Examples
<br />#FILE: /etc/apache2/sites-available/websiteA<br />NameVirtualHost websiteA:80<br /><br /><[virtualhost websiteA:80]><br />ServerAdmin ravi@localhost<br />ServerName websiteA<br />DocumentRoot /var/www/websiteA/<br /><directory><br />Options FollowSymLinks<br />AllowOverride None<br /><[/directory]><br /><[directory /var/www/websiteA/]><br />Options Indexes FollowSymLinks MultiViews<br />AllowOverride None<br />Order allow,deny<br />allow from all<br />...<br /><[/directory]><br />...<br />...<br /><[/virtualhost]> <br />

ServerName indicates the name (or alias) with which your site has to be recognised. Usually a webserver will be hosting multiple sites with different domain names on the same machine. At such times, the webserver distinguishes between different websites through the ServerName directive.
you will be giving it your domain name say like www.mysite.com or something.

The DocumentRoot option denotes which files to be served when the server name is entered in the web browser. This usually points to the place where you have stored your website files.