An RSS (Really Simple Syndication) feed is really a simple version of a web page. Typically, RSS is used to show news headlines, but it can be used for any information you can present in a list. The advantage of RSS is that the feed is automatically updated whenever new content appears, so you don't have to keep visiting a website.
Using RSS feeds, you can find out instantly whenever a new job, car or home appears that matches any of your searches. This means that you don't have to remember your searches, and you don't have to type them in again.
You can read RSS feeds using a "news reader"; this can either be your usual web browser (IE, Safari etc.), or a special piece of software that gives you better control over the feeds to which you subscribe. Here are a few options:
In addition to the above-mentioned RSS readers, there now exist several web-based RSS readers. MSN, Yahoo!, and Google are among the websites offering you the chance to collect RSS feeds in an area on your homepage there for easy browsing.