Torque is the amount of rotational effort exerted at the crankshaft by an engine. The unit of measure is a pound-foot, which represents a force of one pound acting at right angles at the end of an arm one foot long.
"Torque gets it going, and Horsepower keeps it going."
Torque is used for moving from a standing stop; such as pulling a boat out of the water. Torque is the force that throws you back in your seat when you stomp on the gas. Horsepower is used for things like towing a trailer over a distance. Horsepower also creates a vehicle's top-end speed.