Time zones – the undoing of many developers’ sense of sanity. Get them right and most likely your users won’t even notice. Get them wrong and you can end up increasing racial tensions in the Middle East. As we embed ourselves further into this Brave New World of JS Everywhere, let us not forget the basic lessons from before JS existed. This talk will explain the oddities, pitfalls, and ever-changing nature of time zones, so that you may learn from my mistakes (I wasn’t kidding about the Middle East bit).