Very few members here seem to be using RSS, so I've decided to write up an RSS tutorial for beginners. If it's not new to you, then at the end you may find some tips for advanced RSS users that you might be interested in.
What is RSS?
RSS stands for "Really Simple Syndication" (and ironically also "Rich Site Summary" proving that geeks can make even simple things like acronyms complicated). It references a collection of protocols used for web feeds.
It can be used for a variety of things but the main use tends to be for getting content feeds from various websites. So this tutorial is going to focus on that use, where you are trying to aggregate various sources in one place.
How do you use RSS?
Because RSS is just a collection of protocols you can use it a variety of ways, for example a webmaster can use it to syndicate content from another website. But here I will focus on how the end user consumes an RSS feed.
First of all, you use an RSS reader. RSS protocols look similar to HTML and you need a reader to format that in a way that is useful to you. RSS readers can easily be divided into two camps: desktop RSS readers and browser-based RSS readers.
The online RSS readers have the primary advantage of being available to you from any internet-connected browser while the desktop RSS readers are sometimes faster and richer applications similar to a desktop mail reader or are even built into the browser or added to the browser as a plugin.
What you prefer depends on your own use cases, and it's a similar decision to whether you use webmail or desktop mail. I use web versions so that all my data is available to me at any computer but if portability isn't a big deal to you then you may prefer a desktop reader.
So here are some recommendations:
Web Based RSS Readers
Similar in presentation to Gmail this is a very fast and powerful RSS reader. The layout is similar to a webmail application, so you can see all the feeds mixed into one or you can see specific feeds alone. Google also has iGoogle for the start-page format of web RSS (see below).
This is the dashboard/widget style of online RSS readers, that allows you to mix web widgets with RSS and make pages of custom content and applications. These are best described as "start pages".
There are many many more examples out there but these are two very good ones for the two different types. The advantage of the email reader layout is that you get RSS and nothing more, and all the space is dedicated to the feeds. The start pages can be dramatically customized and you can have widgets like search, weather, games and more on your start page.
Desktop Based RSS Readers
I don't have a lot of experience with these, as I started moving to a webtop before using RSS extensively so here are a few well regarded desktop readers.
For Windows users this Outlook-like desktop reader will be familiar in layout.
By the same company, this Mac client integrates well with the Mac OS and is a popular option for mac users.
How do I find and subscribe to feeds?
Depending on the tool you use, you may have a database of feeds pre-subscribed to, or even tools to search for feeds right in the reader itself. But you can also find RSS feeds on most blogs and news sites if you look for the RSS icon:
That icon is usually linked to their feed url, which you can copy and use to subscribe to in your feed reader. How you actually subscribe depends on the reader you choose but it's usually pretty straightforward.
Here is an example feed from able2know:
It probably doesn't look good in your browser, but copy that into your RSS reader and you can subscribe easily. Then you can add other good blogs and news sources that you like and follow them all from one place.
Advanced Users/Other Tips
RSS 2 Email
I'll start this "other" section with a couple of tips for users who would prefer email updates to RSS feeds. RSS can do many things and there are services out there that will consume an RSS feed and provide you with email updates. I don't want them in my email inbox but you might not mind it and these may be good options for you. A popular service for this is: http://www.rssfwd.com/
If you use a smartphone RSS is a good fit for mobile internet use. There are a variety of mobile RSS readers available for the popular smartphone platforms and the simple excerpts work well on the smaller phone screens.
Mashing Up RSS feeds
Note: this last stuff is less useful for end users than for developers and power users who are dabbling in web development.
You can use RSS feeds to do a lot of things if you are a programmer but there are also new tools that are making it even easier for non-programmers to do more complex things with RSS. A good example is the web-based service from Yahoo that they call "Pipes". See: http://pipes.yahoo.com/pipes/
You can use a web interface to build and mix and match different feeds and produce one consolidated feed as a simple example of the mashups that are possible.