[gwbas1c]

DST is common throughout the world: The days that it starts and stops vary, both by locale, and by year.

The operating system keeps track of every locale's DST dates, all the way as long as DST has been a thing. When governments change the date, via law changes, the change usually gets passed along in an OS update.

[o11c]

Note that Windows has major bugs here - from memory, it only keeps track of the 2 most recent DST rules, so historical timestamps will be wrong after the rules change twice.

[mook]

Looking at the Wikipedia article, it looks like it's not that popular in Asia and Africa. Lots of places seems to have observed it at some point in the past, though a lot of them seem to have been last century.

https://en.m.wikipedia.org/wiki/Daylight_saving_time_by_coun...

[pritambaral]

Reporting from India here. No DST ever. I still know what DST is and how it works, but I've never had to change clocks due to DST.