As usual, XKCD is dead right and manages to entertain at the same time: DateTime.

I have had the misfortune of trying to implement sane date and time primitives at my last job, as well as dealing with measuring elapsed time with less overhead than clock_gettime(), and it is a nightmare. For a computer, date and time are completely meaningless, bonkers concepts. And god save me from timezones and daylight savings time. You may enjoy this: 5 of the weirdest time zone facts