Hit

From wow.incgamers.com

There is not a given chance to hit. If an attack does not miss, crits, is blocked, is dodged, is parried, it will "hit" with physical damage. With enough high values of any of the previous types of effect, there can theoretically be a 0 chance to hit.

The +Hit value on items does not increase the hit amount, but rather decrease the amount of misses. There is greater chance of missing mobs with higher level than yourself. It is easier to hit a player than a mob.