RSS stands for Really Simple Syndication. It originally stood for Rich Site Summary.
In essence, it is a way of bringing the bits of the web that you like to you rather than you going out and looking them up.
Here’s the technology:
A piece of content on a website is put onto an RSS feed. Whenever a new piece of content is added, the RSS feed advertises this to any RSS readers that are subscribed to it. The subscribed RSS readers then present it to their users very much in the manner that email is presented.
This great video comes from The Common Craft Show and explains RSS in an amusing and succinct way – enjoy!