Originally Posted by leicam5
First, "gaffer" is a term used for the person who manages the lights on a movie set. (TV and broadcast set too I suppose).
Gaffers tape is a strong fabric tape. It's primary advantage is that, unless left on for a long time, it does not leave any adhesive residue. I've seen it in black and in white 2 inch wide rolls.
It's typically about double the cost of good duct tape and 3-4 times the cost of cheap duct tape.
Here's more info: http://en.wikipedia.org/wiki/Gaffer_tape