Both Cuba and Puerto Rico claim to have originated the salsa. The dance found its way to America through Latino immigrants living in New York City in the 1950s. This was right on the heels of the popularity of swing dance, so people were used to fast-paced partner dancing, and the salsa quickly caught on.
Unlike the waltz and swing, which require a lot of room, salsa can be done in a crowded space because it is basically a rotational dance. The partners rotate each other as individuals, and the partners dance in rotation around an imaginary axis that is right between them.
Mastering the footwork is key to doing the dance. The heels of the foot are kept low to the ground so the step is almost a shuffle. These grounded footsteps and the rhythmic steps are reflective of African influence. This is in contrast to swing dance, where you life your foot and point. Also, while swing and waltz have large strides, the stride of the salsa is small.
Movement in the salsa is from the belly button down. By bending and straightening your knees as you step, your hips will automatically sway. Salsa music has 180-210 beats per minute, so the movement is very fast.