Related Alliance-friendly faction: The Stormpike Guard
Related Horde-friendly faction: The Frostwolf Clan
High in the hills of Hillsbrad lies Alterac valley, the first battleground. The object of this 40v40 battleground is to capture enemy territory and eventually to kill their racial leader. Stealing their graveyards will allow your units to spawn closer to battle, and destroying their armories and buildings will result in less support. Many sidequests and results from raiding include gaining special elite summons and more NPCs which you can turn in the various scraps and pieces found off dead enemy players.
Capturing a graveyard or destroying a territory isn't easy, many opposing npc enemies will be there to protect it. Some graveyards can be cleverly captured by having a team mate lure the guards away, perhaps 'kiting' them, while you steal the flag located at that position. Such an action requires uninterruption, and afterwards you will need to maintain a presense for your faction to claim it.
An easy method of gaining reputation in this battleground is looting an enemy player to recover some racial loot that they carry, which you can then turn in to you main town's NPCs. Your main town will also carry many other quests which you can do while fighting your enemies.
Teamwork is a large part of Alterac Valley; the sheer magnitude of the opposing factions makes it easy to think that your part is relatively small, when in fact it is as large as everyone else's. It only takes one person to leak through to destroy a building or steal a graveyard. Often guilds will join as a pre-formed raid group, ensuring teamwork. This method usually works better.