RSS readers allow you to collect the articles of specific sources in one app, making it a lot easier to find the content you’re interested in without crawling through a lot of noise. RSS (which may stand for Really Simple Syndication, Rich Site Summary, or one of several other possibilities — nobody seems sure) has been around a while, having been first developed in 1999, although it wasn’t more widely adopted until a few years later.
Still using feedly since the google reader death, I just hate how browsers stopped doing RSS natively, it was great having the little folders of the sites I love right in the bookmarks bar.