RSS is an acronym for Really Simple Syndication. It brings new content to you instead of you having to go to it. It is a way for web sites such as CNN, Yahoo, New York Times, and even schmahl.net to send brief descriptions of new or changed content on their web site along with a link to the full story or referenced page.
RSS is a very useful way of quickly getting content you care about. Many information junkies, myself included, used to have countless favorites or bookmarks in their browsers in an effort to stay abreast of news, hobbies, work related items, and so forth. At one time I even went to the trouble of making a sub-domain with some of my often visited sites. Needless to say, using RSS feeds made that site obsolete and it has been deleted.
As mentioned earlier and worth repeating, once sites with RSS feeds are configured into a browser such as Firefox’s live bookmarks, into Outlook, or with a standalone program such as RSS Bandit you no longer have to go to the sites to find new information, the new information comes to you. Programs or plug-ins that collect the RSS feeds are often called aggregators or readers.
In December, 2005, Microsoft and a host of others reached a consensus that this icon 
will be used to indicate a site with RSS feeds. Standardizing on the same icon will reduce confusion, eventually. Until all sites with feeds update, expect to continue seeing icons similar to this 
or to this 
to indicate the XML programming code that makes it work. Depending on your method of aggregating your RSS feeds, either clicking on the icon while your RSS program is running or right clicking it to select copy location, and then pasting it into your RSS program will add the site to your aggregator.
Because of so many browsers and updates to them, it’s futile to try and keep updated information on how to add feeds to each. Instead, simply use your search engine of choice and query RSS feeds in _____________, filling the blank with Chrome, Firefox, or whatever browser is your choice.
Your choice of an aggregator will depend on your personal choice. The personal choices depend on if you want a plug-in for an existing program such as your e-mail program, a standalone program, if will you want to synchronize feeds you’ve read between multiple computers, and layout features. I favor Feedly because I can log into it from anywhere to keep up with feeds without going to the trouble of installing a program on multiple computers and keeping the feeds synchronized.
Further reading and useful links:
https://en.wikipedia.org/wiki/RSS Wikipedia article about RSS
https://www.wired.com/story/best-rss-feed-readers/ Nice Wired Magazine review of RSS Readers
http://www.feedly.com Nice integration into Chrome, my current go-to
http://www.rssbandit.org RSS Bandit’s home page, a standalone application