Wide, canvas-backed tape with a strong rubber-based adhesive. Very commonly used in the United States for everything from taping boxes to vehicle repair

This (initially) sticky tape is unfortunately the most common material used to seal duct connections. Care must be taken when it's applied. For effective sealing, the surface it is applied to must be clean--free of dust, dirt, oil, or other substances. Duct tape has a tendency to lose adhesion with age, especially when used on ducts in unconditioned spaces.

a wide silvery adhesive tape intended to seal joints in sheet metal duct work but having many other uses; "duct tape holds the world together"

Used when nothing else will work.