VirtueMart is an Open Source E-Commerce solution (a Component or Plug-in) for the Joomla! Content Management System. It can be run as a Shopping Cart, or in Catalog mode.
You need to install Joomla! first (as the "Framework"), and then install & configure VirtueMart.
What exactly is VirtueMart?
VirtueMart is a complete eCommerce solution. It must be used together with the Content Management System Joomla!. Both are released under the GNU General Public License, which means by the end, they are free for download and use. Joomla! and VirtueMart are written in PHP and made for easy use in a PHP / MySQL environment. All you need is to download the latest Joomla distribution from www.joomla.org and the VirtueMart package from this site. Joomla provides the Core System and the Framework, which VirtueMart can use. So you can easily use a complete Shopping Cart Solution within your own dynamic Website ("Portal"), together with many other Plug-Ins, called Components and Modules, like Forums, FAQ, Guestbooks, Galleries........
Change the look and feel of your site by using the Templates for Joomla! Sites, which use CSS and XHTML......all these Templates and Plug-Ins are available on extensions.joomla.org (mostly for free).
Even if you think that you don't need a Portal or a "big" CMS - think about and just try it! You are more flexible with it.