Originally it was called Duck Tape.
Duct tape is that sticky, often silver, tape you use all over the house or work place (and even carry in your car for emergency radiator hose repairs).
It was invented in the 1940s because soldiers serving in World War II needed a tape to keep their ammunition dry. Because it's water resistant, it was called "duck" tape.
After World War II the spelling changed to "duct" tape because it was used more often on heating and air-conditioning ducts.
