The three main types of websites that use RSS (really simple syndication) technology are blogs, news websites, and search engines. These are not the only websites that use them, but these are the websites with the most use for a business owner, at least right now.
Furthermore, while most blogs, news sites, and search engines use RSS, not all of them do. So how can you tell if the site you are looking at offers an RSS feed for your Newsreader?
Some RSS Newsreaders are able to detect whether or not there is a feed available on a website. Simply copy and paste the web address (URL) of the page you are on into your Newsreader, and it will tell you whether or not this page has a feed. Beware though, not every Newsreader is capable of doing this, and even if the website has a feed, the particular page you are on may not indicate the existence of the feed to your Newsreader.
For example, when I am on the internet, I use the Google toolbar in my Firefox browser. There is a 'Subscribe' button on the toolbar that appears orange when there is an RSS feed available for the page I'm on, gray when there isn't.

Clicking the button automatically adds the feed to one of seven Newsreaders that you select from a list. In addition to the Google toolbar, Firefox has a similar RSS feed indicator in the address bar:
Internet Explorer (version 7+) includes an RSS button near the tabs:
If you haven't noticed a common theme here, it's that a webpage with an RSS feed is represented by the little orange square
that is now a standard on the internet.
If the options above are not indicating the page you are reading has an RSS feed (or if you don't use these options), you can usually manually find the feed on the page if it offers one. For example, on this blog, you will find the icon for the feed in the sidebar under the heading 'subscribe.'
Subscribe means one of two things on a webpage: 1) the page has an RSS feed and this link leads you to that feed, or 2) this page can be subscribed to through daily emails. Sometimes it means both. Usually this is the link to the page's RSS feed.
Some webpages don't use the standard icon to indicate a feed. This is usually due to the author of a blog using one type of RSS Reader (like My Yahoo! for example) and believing that most of the world uses the same RSS Reader (not a good thing to assume). In this case, the blogger might use the Yahoo! feed icon instead of the standard icon:
While this may mean something to those readers who actually use My Yahoo! to track RSS feeds, it means nothing to the rest of us who track feeds with a different reader. As a result, you may find sites that list multiple icons:

This approach tends to clutter a blog and isn't as useful as the author of the blog might hope. Displaying the standard RSS icon is just fine, more elegant than this collage of icons, and isn't likely to frustrate the person who uses the one RSS Reader you have forgotten to include.
Finally, RSS may not even be called 'RSS' on some webpages. It may be called 'Atom,' or 'RDF,' or 'XML' on some webpages. Don't be fooled, they are still RSS, just specific types of RSS. Every major Newsreader can use these types of feeds and produce the same end result with them.
Some websites even offer you a choice of two of these technologies (RSS or Atom, for example), but your RSS Reader really doesn't care which you choose. Why do they offer a choice? Because they can. In the old days (2 years ago), it may have made a difference in what the feed would produce. These days, it doesn't really matter.
When you click on one of these links, whether it's the RSS icon, the word 'Atom', or the word 'subscribe,' you are usually brought to the RSS feed for that website. It looks like the page you were on, just stripped of some of its format. When you reach this page, copy and paste the web address (URL) of this page and load it into your Newsreader. This is the page the Newsreader is going to display from now on. Load 20 blogs, or a Google Blog search, or the top stories from your favorite paper this way, and you may never have to visit the actual sites they came from ever again.
Next time, we'll look at exactly how the RSS feed is loaded into your Newsreader.