Every backend developer has shipped a date bug.

A timestamp that's off by an hour. A report that's missing yesterday's data, but only for some users. A meeting reminder that fires at 3 AM. A duration that somehow comes back negative.

The worst part is that these bugs rarely fail where you expect them to. Everything works on your machine. The tests pass. Then somebody in another time zone hits one Sunday in October or March, and suddenly your perfectly reasonable code starts doing impossible things.

This talk is a live bug hunt. We'll reproduce these failures on stage, watch them happen, and then figure out what actually went wrong.

In the end, all of these bugs come down to one distinction: a moment in time versus what a clock on the wall says. Once that clicks, a lot of date and time APIs suddenly make much more sense. I'll also leave you with a small checklist that helps answer a simple question whenever you're working with time: what exactly am I trying to represent?