■ Don't confuse this with the shorter (in sound) も which means "also." This もう means "already" (something has already happened) or, with a negative verb, "not anymore" (done in the past but not now).
HOW to use:
■ Since もう isn't tied to a specific verb or noun, it can be used in various positions in the sentence, but it is usually at the beginning of the sentence. Also, with the "not anymore" meaning, finish with a negative verb.