As the name suggests, this is a fast one. With lots of fancy footwork as you fly around the floor, it needs to travel at top speed whilst at the same time displaying intricate and accurate footwork. When danced well, it should still look smooth and easy even though your heart will be thumping like crazy.
This is generally thought to have started as a development from Foxtrot as the popular music of the day got faster and wilder, so the dance styles sped up too. A lot of the faster music that could be used for Swing can also be used to dance Quickstep.