The time zones give "the specific areas on give specific areas on the Earth a time of day that is earlier or later than the neighboring time zones. This is because when it is day-time on one side of the Earth, it is night-time on the other side. There are 39 time zones dividing the Earth into different times, each with its own name, like the North American Eastern Time Zone." - from Simple English in Wikipedia.
Google Calendar has built in the feature, which is called "Swap Time Zone." It is useful for the everyone who often travels. It does not affect the event time which is in time zone when you create the events in the place, you just need to swap the time zone when you travel.
For example, you created the Happy Hour event and invited all friends in Toronto, but you will go to Tokyo soon and do not want to affect your family event in Tokyo. You can use the swap time zone feature to solve this problem.
Here is how to set up the time zone and swap it:
1. Click the Gear icon
2. Click the Settings
3. Set up the additional time zone you travel in.
4. Click "Swap"
5. Click "Save"
Here is a screenshot that show how to set up:
6. Done. Good luck on travel.