RSS - A Brief Intro
RSS is 'Really Simple Syndication'. It allows visitors to your blog to have your posts sent to them automatically with a method of their choosing, instead of having to come to your web page each day to look for an update. This can be helpful if someone follows several blogs as they can use the RSS reader tool to look at all the blogs in just one place.
The RSS feed is a unique URL published by the blog, this is what is needed for your visitors to subscribe to your blog with RSS. You'll be glad to hear that there is very little to do, as all the blog platforms have the RSS technology already built in, including WordPress. In fact, chances are you won't have to do anything if you have already chosen your theme.