When resident of Australia are sleeping, people of India might be enjoying Chai/Coffee in the late afternoon and people of London might be having lunch and in Ney York it’s time to get up.
Having said that, the entire world is distributed in so many time zones, I think they might be more than 24 time zones in the world, there are some time zones are just 30 or 45 minutes apart.
Time zones in world are balance from Coordinated Universal Time (UTC) by a number of hours (UTC−12 to UTC+14).
In USA & Canada there are 6 time zones and there is a concept of Day light saving which is observed in so many countries.
Once you have decided to travel to different Country or state or city, check the time zones where that location fall, this will help you to plan your flight, Stay there and be in touch with important stuff in your home region.
You guys can you multiple website for the same or just type in Google “Time in your destination”, I will recommend https://www.timeanddate.com for keeping a track on different time zones.
If you guys want to read more technicality about Time Zone, just read the page on Wiki about Time Zone, here is the link https://en.wikipedia.org/wiki/Time_zone