What is electrical insulation tape officially for?
Four ways electricians use black vinyl 'electrical tape':

Wrap around an outlet or switch, to cover the live electrical terminals, before stuffing the outlet or switch into its electrical box.  This prevents surprises in later opening the (possibly live) box, and protects against contact with the bare ground wire in that box.   Other 'live' metal (like big splices) gets more elaborate treatment, but taped twisted-wire splices are sometimes encountered in elderly wiring.

Repair loose insulation (old cloth especially) when reworking an old device.   Sometimes even covering a nicked or scorched bit of damaged insulation, if
replacement is not feasible.

Identifying different wiring use: if you run a black/white/green cable to
a distant switch, the white wire is not 'neutral', but 'switched hot', so is given
a wrap of black tape to mark this variant function.  Green (or bare) cannot be
given a different use, it can ONLY be ground.

Pulling wires, like in a conduit, with a steel 'fish tape'.  You twist the wire into the fish tape's end, then cover the edges of the assembly with vinyl tape so it doesn't catch.   At the end of a big job, there's a lot of short twists of wire with
black tape, and maybe pulling lube, in the discard bin.