Questions about Time Zones

GMT is also known as Greenwitch Mean Time. Other time zones are calculated by adding or subtracting the number of hours from GMT.
For example, in the United States, Eastern Time is GMT - 5. (So, when it's 19:00 GMT, it's 12:00 Eastern Time). Current GMT time is:

Current Time UTC/GMT

Hopefully this converter will be useful to some - I'm not 100% sure if it takes into account Daylight Savings Time: