About EST versus EDT
Here in the US we have the system of daylight savings time (DST), at least for now.
But did you know that the timezone you use includes that? Cause I sure didn't.
EST/CST/MST/etc are for the standard time version of the time zone EDT/CDT/MDT/etc are for the DST adjusted periods!
Largely, I prefer to let libraries handle this for me, so I've never dug into the details. But this one is also interesting from the perspective of communications with others.