Dave Shea does it again, this time effectively explaining RSS/Atom/Syndication in clear, easy-to-understand words.
People like Shea are the best at writing these types of things; designers who have to design good, solid interfaces are used to breaking down an idea into its elements and effectively using illustrations, words, and context cues to make the explanation.
Shea also makes a great point: “XML is the base technology both are built on, but that’s almost totally irrelevant; the orange buttons are mislabelled, and should read ‘RSS’ or ‘Atom’ instead. Strange, but true.” I never have published an orange XML button—I usually note what feed standard is used. [That reminds me that I need to put my Atom feed down at the bottom here.]