User blog comment:Dentface/Revive POTCO - ALL DAY EVENT - Land Ho! An Island for An Email/@comment-173.21.132.174-20130518194420/@comment-1140008-20130518212054

GMT means Greenwich Mean Time.

It's the timezone for London and the surrounding areas.

EST is states on the east coast of the US, like New York and Florida.

PST is for states on the west coast like California.

In-between is Mountain time, which is one hour ahead of PST. Which includes states like Utah.

After that is Central time, which is an hour ahead of Mountain time, and an hour behind EST. States include Kansas.