I am shocked when I meet an American who actually knows when to use PDT as opposed to PST. They also think they're being clever asking if I want to have a meeting at X:00 GMT when they mean BST (or Irish Standard Time, which is confusingly observer in Ireland in the _summer_, which is 1 hour ahead of GMT just like BST is).

Of course, when the S can mean either "summer" or "standard" one can forgive some confusion.

I've switched to 3PM ET or, better yet, 3PM New York time.

Sadly, that's because they think UTC == GMT (which does have DST). UTC would be the time that computer software operates in and then feeds humans 'human time'.

You also can't use 'Zulu' from https://en.wikipedia.org/wiki/List_of_military_time_zones either, for that same confusion.

The problem, like with driving, is that humans are communicating the time to humans, instead of the 'smartest' humans having programmed computers how to convey time for the rest of the humans.

GMT has always zero offset from UTC. During daylight saving, the UK switches to another time zone called BST, with an offset of +1h. Other countries might call their summer time zone with a different name.

UTC != GMT because the former is not a time zone but a time standard. No country uses UTC as a time zone because UTC is not a time zone. All times in the GMT time zone are numerically equal to times expressed in UTC though.

GMT doesn't exactly have BST; rather, many places that observe GMT in the winter observe BST (which is defined as GMT +1 hour) in the summer.

Google is not the arbiter of all things, but a good clue is that Googling "current time GMT" in the summer will give you the time in Britain as though DST didn't exist.

GMT doesn't change throughout the year. Birtain uses GMT during winter and BST(UTC+1) during summer though.

https://www.timeanddate.com/time/gmt-utc-time.html