According to Wikipedia towing is the process of coupling one object to another’s, so that one can be pulled along behind the other. The towing source (lead object) is usually a truck or other motorized land vehicle. The coupling may consist of a chain, rope, bar, integrated platform, or some other means of keeping the two objects together while in motion.
So, that being said, not just cars and trucks can be towed but almost anything that will move can be towed.
Just remember that not all vehicles are made to tow and the safety considerations of properly towing another vehicle or object cannot be understated.