Lightweight Directory Access Protocol (LDAP) is a protocol designed to access directory systems over TCP/IP. Because of this various databases provide an LDAP interface such as Microsoft's Active Directory, Novell's eDirectory, as well as more dedicated LDAP solutions such as OpenLDAP.

Joomla! has had a native LDAP library (joomla.client.ldap (changed to JClientLDAP in Joomla 3.x)) and a native LDAP authentication plugin. This allows Joomla! to authenticate against LDAP systems out of the box: to configure, go to the Plugin Manager and enable and edit the Authentication - LDAP plugin.

You can also read a tutorial on getting started from scratch with LDAP.

Reference: http://docs.joomla.org/Glossary

RSS (which stands for, among other things, Really Simple Syndication) that allows you to syndicate your site content. It defines an easy way to share and view headlines and content through newsfeeds. You can find RSS feeds in hundreds of thousands of places on the Internet which allow you to stream their articles into RSS readers - or your Joomla site.

The Feed Display module allows you to display other sites’ RSS feeds on your site, which is a great way to keep your content from being static.