The Equator is a line of latitude that goes around the middle of the Earth. The Equator is equidistant from both geographical poles at all locations along it. It measures 24,902 miles in distance and is represented as 0° of latitude.
The Equator goes through some countries, like Ecuador (which is named for it) and Zaire, but it does not go through the United States. Florida is the state closest to the Equator in the continental United States. Hawaii is closer.
Just as Polaris is almost exactly on the celestial North Pole, the "belt" of the constellation Orion is almost exactly on the celestial equator. If you see Orion's belt is directly overhead, you know you are on the Equator. Early Polynesian seafarers may have used it for navigation.
In the British and U. S. navies, a long-standing naval tradition calls for a fraternity-like initiation ceremony when a sailor crosses the equator for the first time.