I have had a few people ask me lately what exactly is a blog feed or an RSS feed, how to subscribe and why they should. Many web sites and blogs offer RSS feed subscription so that people can be notified when there is new content. You can subscribe to get an email of new information, but generally that email would only be sent once a day showing the new content.
If you wish to receive new content as it happens, you can use a feed reader - which will tell you when there is something new on your favorite sites that have RSS feeds. There are several feed readers out there, I use Google Reader. Just set up an account with Google if you don't already have one (free!) and then pick which feeds you wish to subscribe to through the reader. You can also subscribe to the RSS feeds on your chosen web page (if it has one) by clicking on the feed button.
Most are located toward the top of the site. Mine is up to the right. You can also choose to subscribe to the rss feed of a comment stream of a post if you so choose. 
You may also see a button that looks like this as well.
There are other variations as well.
If you have a feed reader and subscribe to my rss feed for this blog, then your feed reader will tell you when their is something new. I have enjoyed my feed reader. I subscribe to all sorts of business feeds, real estate industry feeds, sports feeds, and local news feeds. It saves me time as I don't need to keep checking sites to see what's new.
This video from Lee LeFever of Common Craft may help explain it further.
Happy Reading.
