Tape is immensely useful for a film set, but it can't be just any tape, oh no, it has to be a superior tape in many aspects.
Enter: Gaffer's Tape
If i were to pick Gaff tape's closet relative, i'd say it would be masking/painters tape. They have the same core principle: Be sticky, but come off easily and with no residue. Gaff tape is one of the most beloved tools on a film set, and considering how pricey some brands are, don't be surprised if you come across folks who are very wary about sharing their roll with you.
So why not buy masking/painters tape? Good question:
Gaffer's tape is a thick tape, it has a good amount of strength to it, it's far more like duct tape than masking/painters tape in the durability arena.
It comes in black, white, red, green, blue, and quite a few others. Each has a specific purpose and is solid with no other design, which is very important especially for certain uses. Some uses listed below. Aside from black, it's fairly easy to write on Gaff tape, white usually being the best for labeling. You don't need to obsess about having every color, especially if you're just a casual shooter/on small sets/etc... You can imagine how hollywood and broadway sets can have the whole rainbow, but be realistic about your needs. For many folks, having just black and white will suffice perfectly fine.
Like painters/masking tape, it is meant to be sticky, but come off easily with no residue. But Masking/Painters tape is designed for walls, and is generally built to be stuck just once. Gaffer's tape can be stuck, restuck, and stuck again, and still maintain much of its stickiness. Rain? No problem with gaffers tape, of course trying to tape a surface that's already wet isn't going to work very well, but if it's already taped up, water has to try really hard to dislodge gaff tape.
Gaffer's tape comes in various widths: 1/2", 1", 2", 3", 4". Which do you need? Depends on what you're doing with it. For my needs, i prefer 1". 1/2" are arguably the most useful for marking actor/camera/set pieces, and come in the widest variety of colors to differentiate between each marking. The most commonly used is probably 2", and the great thing about Gaff tape, is that it's pretty easy to rip narrower strips out of a wider tape.
So what can gaff tape be used for?
There is no way to document the entire world of possibility of how you can use gaffers tape. You can find folks standing around a film set on lunch break swapping stories on the wacky ways they've used it. Here are some of the more typical uses:
-Lens pull marks
-Securing cables, everywhere
-Impromptu lens flag
-And all the other general things you could use tape for.
OK, so Gaff tape is great, but different brands of Gaff tape vary in their quality, this is where the advice of a Gaffer, and reviews on Amazon come in. Suffice it to say, even the cheaper brands of gaff tape will be better than painters/masking tape, and even traditional duct tape just for the reason of residue.
Buy some damn gaffers tape! You don't need to be a gaffer either. ACs, DPs, and others keep gaff tape with them at all times for their various needs.