What are feeds RSS, XML, Atom?

“Feeds are a way for websites large and small to distribute their content well beyond just visitors using browsers. Feeds permit subscription to regular updates, delivered automatically via a web portal, news reader, or in some cases good old email. Feeds also make it possible for site content to be packaged into “widgets,” “gadgets,” mobile devices, and other bite-sized technologies that make it possible to display blogs, podcasts, and major news/sports/weather/whatever headlines just about anywhere.”