Gaffer Tape (also Gaffa) is a fabric backed tape used in the entertainment industry for pretty much anything - particularly for securing loose cables on the floor, to prevent trip hazards. It is important to use high quality gaffer tape, as cheap gaffer normally ends up too sticky (in which case, it leaves gaffer gunk on the cables), or not sticky enough (in which case, it won't stick the required materials together.
Available in various sizes and colours, 50mm being the most common and useful width.
Gaffer has an almost cult-like following and has been known to appear in certain alternative photographs.
LeMark are one of the primary manufacturers of Gaffer tape in the UK, producing a large range of colours.
"You know, television was actually invented in the 1890s, but they couldn't get it to work until the '40s when they came out with gaffer tape." - Walter Pyle of CBS.