-What: RSS feeders. Look for term in an encyclopedia for web terms, search in forums to see what people say about it, look into Google news to know latest about it. -Who: creators or users of RSS feeders. In this case you're not interested in Who. -When: we can think of when it all started (history, but we're not interested on this now) or when they are used, which is when a new piece of information is produced and fed to individuals' computer interfaces. -Where: over Internet. -Why: you could answer this question if you want to go philosophical. For purpose of search, you would have already found what you want.

So next time that you have to do a search about anything, do it by answering these questions and looking into places that can answer it straight. You will obtain much more useful information in a much quicker way.