What is an ABC watch and do I actually need one for hiking?

ABC stands for altimeter, barometer and compass — the three sensors most useful for backcountry navigation and weather-watching. If you hike off-trail, scramble, mountaineer, or want to track elevation gain and incoming pressure drops, an ABC watch earns its keep. For groomed-trail day hiking with a phone, a basic GPS watch or even a field watch is usually enough.