Since we're directly north of the USA, much of Canada is in the same time zones as the US time zones. We do extend further east, so we do have an extra time zone and a half.
"Atlantic" time includes the Maritime provinces: New Brunswick, Nova Scotia, and Prince Edward Island, as well as Labrador. They are an hour later than Eastern time. The island of Newfoundland has its own time zone a half hour later than Atlantic time.
I hope that made sense!
Lesson learned: never forget good ol' Canada
Anyway I'm in Ontario specifically, so my timezone is eastern. This timezone also applies to places such as NY and Michigan for the United states.