Really Simple Syndication or Rich Site Summary (RSS) is a type of web feed that allows users and applications to access updates to online content in a standardized, computer-readable format. This allows users to keep track of various websites in a single aggregator.
It can be a powerful tool to spread your message out to a broader audience, boost exposure online, and even help save time in performing your internet marketing tasks.
A perfect example of this is news outlets. Virtually all have an RSS Feed, which is a broadcast in data format that includes everything they publish on their news sites. Aggregators, search engines, and other news outlets may then monitor those feeds or even tap into them to publish them elsewhere.
Virtually every blogging platform includes an RSS feed, and smart web developers include one on websites that feature e-commerce functionality. Consider the things that can be done with your syndicated feed online.
If you keep your message alive on a regular basis through a blog, you can use the RSS feed to provide added value to every blog post you publish. The feed can be plugged into your Facebook and Twitter accounts; displayed on your other web properties; and, should you take the time to list your RSS feed in online directories, the news aggregators and internet publishers of the world will be able to discover it and publish your content elsewhere.
Much like an RSS feed coming from a blog, an e-commerce platform that includes a feed can do the same. Consider the benefit and added value to each product you add to the system. For example, when I add a new T-shirt to my online store, I have the feed from that store plugged into Facebook, Twitter, my blog, and two other web properties. With that single press of the button to add an item to my shop, I have published that product to a handful of other properties and increased my reach. It has also multiplied the content, increasing its chances of discovery by internet users, search engines, and web crawlers.
Sources: Kelly "Rags" Ragland/Wikipedia