Us Yanks (and Canucks, eh?) use the term "flashlight", but everywhere else in the English-speaking world, it's called a "torch".
Normally I'm pretty good at translating British to American, but today an English colleague of mine quipped "Tap the torch app, would ya?". He caught me off-guard and of course looked at me like I was an idiot before I realized he wanted me to shine my phone on his hands so he could see what he was doing. I just told him not to get his chumbly-wumblys in a tizzy and we had a good laugh about it.
But seriously, I've always wondered how the term "flashlight" came to be and why only North Americans seem to use it. This terribly gaudy website mentions that the earliest lamps used carbon filament bulbs and weak batteries, and could thus only be "flashed" on for a few seconds at a time. But I don't really buy this explanation because these devices were a rare, expensive novelty item in those days and dysphemisms like that usually refer to things that are commonly known (i.e. everybody gets the joke).