This is a technology that is infact a way of "syndicating" content on a website or somewhere. For example, do you read the news headlines every day at the BBC?
Let's pretend you do. So you load up the site, it loads all sorts of stuff you don't want, but you do get the stuff you want. what if you could just get the stuff you want, without anything else.. no adverts, no side links, just the news headlines (and maybe a brief excerpt of the article)? This is what syndication does. One current technology being used for this is called RSS, or Really Simple Syndication. another form is called Atom. both do the same job.
If you read several sites that have syndication, you can use either a program or a website (bloglines.com) to manage these feeds for you. One great thing this also does is it knows when you last checked the site, so you only see the headlines that are new to you, not all the old ones you've already read. Very useful I'm sure you'll agree! Typically you also have the choice of clicking on a link to the actual article on the website, to view a video or something that may be on the website but not the feed (the actual file that you link to in order to get the rss is called the 'feed').
If you get more advanced, imagine this. You have the content in your feed from some website. It's structured in that feed (something called XML, basically its a language to structure data so both humans and computers can understand its meaning). So now you can design some website or program that takes that feed with its content, and you can display it any way you like. For example, I know of a site that grabs a feed from a local weather station. If the feed says that there is blue sky, he makes a picture load on his site with blue sky. If it's dull or raining then the program loads a picture of a dull rainy sky. The feed contains the information, you do what you like with it!
Clever, eh?