From Joomla! Documentation
How Do I Download Joomla?
It is easy to download Joomla! Just go to downloads.joomla.org.
What Some of Joomla's Features?
User Management - Joomla has a registration system that allows users to configure personal options.
Media Manager - The Media Manager is the tool for easily managing media files or folders and you can configure the MIME type settings to handle any type of file.
Language Manager - There is international support for many world languages and UTF-8 encoding.
Banner Management - It's easy to set up banners on your Web site using the Banner Manager, starting with creating a client profile. Contact Management - The Contact Manager helps your users to find the right person and their contact information. It also supports multiple contact forms going to specific individuals as well as groups.
Search - Helps navigate users to most popular search items and provides Joomla administrator with search statistics.
Web Link Management - Providing link resources for site users is simple and you can sort them into categories, even count every click.
Content Management - Joomla's simplified three-tiered system of articles makes organizing your content a snap.
Syndication and Newsfeed Management - With Joomla, it's easy to syndicate your site content, allowing your users to subscribe to new content in their favorite RSS reader. Menu Manager - The Menu Manager allows you to create as many menus and menu items as you need.
Template Management - Templates in Joomla are a powerful way to make your site look exactly the way you want and either use a single template for the entire site or a separate template for each site section.
Integrated Help System - Joomla has a built-in help section to assist users with finding what they need.
System Features - Speedy page loads are possible with page caching, granular-level module caching, and GZIP page compression.
Web Services - With Web services, you can use Remote Procedure Calls (via HTTP and XML).
All of the above with Powerful Extensibility.
Joomla Help and Mail Lists
You can find help on our forum or join one of our mail lists at http://www.joomla.org/mailing-lists.html.