In environments like kitchens and bathrooms where there is likely to be a combination of water and electricity, the best practice is to have both a safety ground and a GFCI-protected circuit.
Remember that a correctly-wired GFCI provides ground fault protection to every outlet "downstream" of it, that is, every outlet hooked up via the LOAD terminals.
In particular if you cannot immediately state the relationships between amps, volts and watts, if they are in any way unclear to you, don't work on power systems until you've internalized them.
You wouldn't want someone who didn't understand the difference between weight and height to work on your house, so don't let someone who doesn't understand the difference between current and potential to work on your wiring.
What if the wiring is faulty such that the hot has electrified the box the neutral wire has broken?
All the grounding systems in a structure have to be bonded to each other.I don't know too much about replacing outlets, only what I've read online or through You Tube videos. Some outlets have been replaced (brand new kitchen) but some are still the old 2 prong.I bought a receptacle tester and tested the newer style outlets, which all tested as correct wiring.The hot (black) wire provides a voltage and therefore delivers current to the appliance plugged into the plug. The safety ground, as its name implies, is there for human life safety; in the event of a fault there is a clear path to ground for the current, rather than it trying to go to ground through the human holding the faulty toaster.You know that the total current through a circuit is constant, so that current has to go somewhere; it goes from the appliance to the neutral (white) wire, which is connected to ground. Let's make sure that's clear: the fundamental purpose of the ground wire is to ensure that even in the unlikely event of a fault, the current passes to ground through the wire, not through a human. Rather, the GFCI contains a detector which measures the difference between the hot and neutral currents.Or, it might be grounded now, but not grounded in the future.People do not think "I might need to rewire the bedroom because I upgraded the plumbing in the bathroom". Second, the metal object might be inadequately grounded.I'm even more confused now that the receptacle tester said that they were correct. *There are actually a few other ways to ground an outlet safely, e.g.with armored cable with a bonding strip or a grounded box plus an outlet that allows grounding through the strap. That's a good start but I would strongly recommend that you learn more before you make potentially safety-impacting changes in your electrical wiring.Third, the metal object might be adequately grounded, but not bonded to the ground for the electrical box.Suppose you have two distinct grounds -- the electrical system ground, and a bit of plumbing -- and they actually physically go to ground at opposite ends of the building, and they are grounded in dry, sandy soil.