An RSS feed allows you to syndicate your content automatically. The RSS feed is usually a standardized XML file format. The feed is good for your visitors who are interested in your content to subscribe to updates from your website. RSS feeds are very common for bloggers. As you create content, the updates are added to your feed. Someone that is following your blog doesnt have to visit your site to check for updates. They use an RSS reader to get the updates. When they see an update that they are interested in, they click on the feed link and the visitor is redirected to your site.
There's software that you can buy to build and manage your feeds. For ASP.NET, i use simple vb.net to build the feed for my site. You can read over this tutorial on how to build an RSS feed for your site. The tutorial covers how to read from your data source where the "news" or the "article" information is stored and how to convert that information into XML format.
After the RSS feed is built, you can use RSS tools to help you manage your feed as an option. For example, feedburner from Google is very common. They track how many subscribe to your feed, and track the statistics for you.