Daylight saving time (DST)
Also called: DST, Summer time
Moving clocks forward in spring and back in autumn, creating a skipped hour and a repeated hour.
Definition
On DST change days one hour doesn't exist (spring) and one hour happens twice (autumn). Alarms, bookings, reminders and "24 hours later" calculations often break on those days. Testers set the device date and time zone to a DST change to check.
In practice
A reminder set for 02:30 on the last Sunday of March never fires in Belgrade, because that time is skipped.
Learn it in context
Lessons that use this term.