Editors Note: It is some time since I wrote this and interestingly wordpress is often a better platform for most standard website functions these days. We still love Joomla for some kinds of function but are doing most sites with wordpress now. View the comparison blog on Wordpress vs Joomla
Joomla is the CMS (Content Management System) that we use to make our sites. It allows the average man to add content to their own web site. Yes it is a bit more complex than using facebook but with some guidance you will be adding pages and new menu items with ease. Even if it is beyond you it allows us to add things remotely to your site. Yes you can add things from your mobile phone or tablet even. You just need a browser and internet connection.
A database stores the content of the site and various options, this data can be added and changed by the CMS so it updates itself. You can choose to save and not publish immediately items and you have access to advance ACL so you can set a piece to be able to be read by certain people for example subscribers who pay a monthly fee to you Joomla ACL will recognise the logged in user has the correct privileges and will show the item for that user or group only.
Joomla has been developed by many individuals using the Open Source Idea which allows the use as given in its license opensourcematters.org.