It's too bad I don't have time for an essay :P Basically it protects (no pun intended) your Pokémon from disruption like Fake Out (very important for Sashed 'mons), Thunder Wave, Will-o-Wisp, et cetera, or powerful attacks like Double-Edge or Earthquake while the Protecting Pokémon's partner takes out the threat on the other side. Protect can be uses to stall the opponent if you just need a bit more Burn or Hail damage. It's also useful for scouting, like if the opposing Salamence has Return or Double-Edge. Pokémon like Ferrothorn and Mega Venusaur use it to get free HP from Leftovers or Leech Seed.