My work needs me to setup computer system to work across the globe. A key issue is to have a common time reference. This gets tricky because of time zone. Just saying 12pm is imprecise. Which time zone is 12pm reference to? Is it 12pm in San Francisco? Or 12pm in London? Another complication is day light saving adjustment, which make time measure more irregular.
The standard practice is to use Coordinated Universal Time (UTC), i.e. Greenwich Mean Time. So everyone across the globe has a reference to the same standard time. Having a standard reference is great for computer system. But for us software engineers it is another quantity to juggle with. I often have to track time across systems. If the system responses something like 14:22, it is still hard to make sense of. Is it this afternoon? This morning? Or sometime in the future? Translating between local time and UTC is often necessity for me. But it is much harder to do mentally compares to, say translating between metrics and imperial unit.
One tip is I added a clock of Reykjavik, Iceland time on my cellphone. Iceland time happens to match UTC and Icelanders do not mess with daylight saving time. This gives me a easy read of current UTC time (8pm now, which is 1pm San Francisco time.)
I have a colleague who argues strongly that the entire world should adopt UTC time in actual daily use and do away with time zone. Standardization is probably very important for him. How practical is this for regular people? To this I said, let's have a meeting at 1am, UTC time (it is 6pm for your reference).