Is timezone just an offset number or “more information”?

Question

I live in a country where they change the time twice a year. That is: there is a period in the year when the offset from UTC is -3 hours (-180 mins) and other period where t

Answer 1

Here's an example of a very popular format for describing timezones (though not what Windows uses).

You can see that it's more than a simple offset. More along the lines of offsets and the set of rules (changing over time) for when to use which offset.