Joomla is data-driven just like most of the other CMS. It is connected to a mysql database.

I've used joomla for a website that I made for my church because it allowed for others in the church to create an account so that they can log in to the site as administrators and edit articles, add new articles, upload images,videos, add modules, etc. from any computer that has internet without them having to know any html.

It is open source which makes it free. It comes with a default template. You can use dreamweaver,web expression, notepad or other site builders to create templates or edit them if you have some good knowledge with CSS,HTML, and PHP. You can also download free templates, or you can buy templates for Joomla.