Time reference
PST vs PDT
Compare Pacific Standard Time and Pacific Daylight Time.
PST vs PDT matters because many everyday scheduling mistakes come from treating time as a fixed label instead of a rule tied to a date, place, and time zone database.
Daylight saving time is the main reason a city pair may not have the same hour difference all year. One region can move clocks while the other stays fixed, or both can move clocks on different dates.
For practical planning, compare the actual event date and use IANA time zone names when possible. Fixed offsets are useful shortcuts, but they can miss daylight saving transitions and local rule changes.
This guide is written for ordinary scheduling, travel, remote work, webinars, and calendar planning. It is not official legal or safety-critical timekeeping advice.
Useful next step
Open the time zone converter when you need to compare an exact date and time. Open the world clock when you only need the current local time.