You can change your time zone at any time in Microsoft Outlook. Changing your time zone in Outlook is equivalent to changing it in Control Panel. This affects all times displayed in Outlook as well as times displayed in other Microsoft Windows-based programs.
You can also add and display a second time zone in Outlook, which is useful when scheduling meetings or conference calls with people in other time zones. When you add a second time zone, the current time in the primary time zone will be highlighted with gradient colors to make it easier to see.
If two time zones are shown, the meeting organizer's time zone is the reference point. If you organize a meeting and display free/busy time (free/busy time: In Calendar, time status and user defined labels are indicated by colors and patterns.) for invitees from other time zones, their busy times adjust to display correctly in your time zone. The second time zone is visible only when viewing days.
Outlook Calendar items' start and end times are stored in terms of Universal Coordinated Time (UTC). UTC was developed as the international time standard. It is similar to Greenwich Mean Time (GMT) except that it observes no daylight saving time (DST) and is based on a 24-hour clock. Zero (0) hours UTC is midnight GMT. The local 24-hour time convention is converted to UTC by adding or subtracting hours based on your location with respect to the prime meridian as well as local daylight saving time considerations.
If you are in one time zone and you send a meeting request to an attendee in a different time zone, the meeting item is displayed at different local times on each person's calendar but at the same absolute time in UTC.
For example, if a meeting organizer is in the Pacific Time zone in the United States and sends out a meeting request that starts at 2:00 P.M. Pacific Time to an attendee in the Mountain Time zone, the attendee will see that the meeting starts at 3:00 P.M. Mountain Time. In both cases the meeting is stored on the respective servers as starting at the same time in UTC (10:00 P.M.).
Note There is no difference in how appointments, meeting items, and all-day events are treated with respect to time zones.