Beast Mastery is the only ranged specialization that can do 100% of its damage while moving. Despite being ranged, most of their damage comes from their pets, which have to be in melee range of the target. The majority of this pet damage is controlled by the Hunter rather than happening automatically. Beast Mastery Hunters are the only specialization that can tame Exotic beasts. In total, there are over 50 different pet families that can be tamed, each with dozens of different looks.
An extremely useful tool for overall optimization
WoWhead Beast Mastery guide
Icy Veins Beast Mastery guide
Noxxic Beast Mastery guide