Honor Points

From wow.incgamers.com

Honor Points are used to trade in for PvP equipment. Formerly known as "Contribution Points". When a player obtains a HK he will be assigned some Honor Points. Points can be gained in 3 ways:

• Killing players of a similar level to yourself.
• Killing racial faction leaders.
• Winning objectives in Battlegrounds (can include killing NPCs).

A high level player killing another high level player will accumulate more points than low lvl players killing each other. You cannot gain honor from killing normal monsters or NPCs.