text: how do time zones work? when do you add or subtract hours and or minutes? time zones are a way of organizing time so that people living in a large area (country, part of continent) share the same time, just to make things easy. people living at about the same longitude usually have about the same local time. there are 25 standard time zones around the world, these are all an integer offset of hours to utc-time, for example, +5 hours or -10 hours to utc. if utc-time is 12:00 (noon/pm), then people having offset +5 hours, have local time 17:00 (or 5:00 pm). then... there are some countries/places not using the standard time zones, they might be 5 hours and 45 minutes ahead of utc, like kathmandu is or some other non-integer offset of hours.