Is a Gulf Sream a cold current or a warm one?

The Gulf stream is warm because most of the water that is caught within the current has been previously warmed by being pushed up through and past the Earth's equator, a geographical circle surrounding the planet. This 'circle' receives a fast amount of heat and sunlight throughout most of the year, allowing the water to warm significantly on it's way towards the northern hemispheres.

While we see much of the movement on the surface of the water as waves, most of the movement of our water around the planet is actually caused by an action called convection. Much like a conveyor belt, cold water sinks and is carried towards (and then away) from the poles and warm water is pushed towards (and then away from) the equator.