I’ve had to get involved with timezones and daylight savings time rules at work recently, while another coworker who usually handles them was out on vacation. It’s a really interesting thing to work on given how most people take it entirely for granted that their computer “knows what time it is.” Take my word for it, a lot of work goes into that particular piece of magic, and it’s very detail-oriented work because you really don’t want to get that wrong.
Anyway, as detail-oriented as it may be, timezones can also be quite interesting. I enjoyed this article about some of the historical anecdotes around timezones.