Summarization:
RSS stands for Real Simple Syndication which will send you updates on blogs that you follow. It will save the time of searching through all the blogs you like to see if there is new info or posts. This way, all updates are sent to one place and you just have to check there for the day.
Application:
I see myself using this for science info. I have a couple sites that send updates to my e-mail already - Spaceweather.com which updates about comets, eclipses, and other events you may want to watch. It's very handy that when something does happen, it notifies me as I often forget to check. I would like to keep up more on other scientific discoveries like the Big Band experiment at CERN (and others) so I don't have to spend the time before I do that unit each year searching out the latest updates.