Oh, how they grow up so fast! EBay—or "the world's biggest garage sale" as most regard it today—celebrated its big 2-1 this year. In 1995, the company founded by Pierre Omidyar went by a different name, though: AuctionWeb. The domain ebay.com would have directed you to an informational landing page for the ebola virus.
EBay wasn't the only notable thing (or even technological thing, for that matter) to turn 21 in 2016. Check out the video above from the mental_floss List Show to hear John Green walk you through all 21 of 'em.