RSS (Really Simple Syndication) is a format used to distribute headlines and similar content across the Internet.
Owners of blogs and other web sites that update their content frequently can make their new posts and content available in files called RSS feeds, which they can submit to an RSS database. Consumers can then use a news-reading service to gather multiple RSS feeds in one place, making it easier and faster to keep up with new information on their favorite sites. RSS feeds typically include a headline and short description of each new item, and they can be distributed to many readers. Readers can scan the headlines and summaries of their collected RSS feeds, then click a link to review the complete article or post.
Syndication describes the process of publishing simultaneously in more than one online location. Many news and other notable web sites already syndicate their content in RSS feeds. Readers find it "really simple" to keep up with these syndicated sites; and it's simple for you to syndicate your content as well.
Why should you syndicate your blog?
Syndication is a great way to build awareness of your content and your brand, drive traffic to your site, and serve your existing readership with relative ease and without expense. An RSS feed can help strengthen your relationship with current readers, who will be able use your feed to stay abreast of your latest blog postings. You can also attract new viewers who might search an RSS database for content like yours and add your blog to their preferred news reader pages.
When you create your blog, it will automatically generate an RSS feed for your site. A link to your RSS feed can be displayed on your site. You can also submit your RSS feed to an RSS database directly or through a plug-in.
For more on RSS feeds and how they relate to WordPress blogs, see this article on the WordPress Codex.