Rug pads are a type of underlayment that goes underneath your rug to protect your floor from damage. They can be made from various materials, including rubber, foam, or cork. A quality rug pad stables and also prevents a rug from slipping around or bunching up.
Rug tapes are used to keep rugs in place. They're usually made from rubber or other types of plastic and come in different widths depending on the size and the heaviness of the carpet you're taping down.