Bungie has introduced a "Refer-a-Friend" program to Destiny, offering exclusive bonuses to existing players and friends they invite to the game.
Provided they're playing on the same platform, both the new recruit and the person who invited them can earn additional experience points through the Link of Friendship, and have access to an exclusive quest, The Hunt for Loot.
Linked Friends will also be able to unlock three new legendary swords called Infinite Edge, the exclusive EV-34 Vector Infinite Sparrow, two team emotes (Duo Dance and High Five), and a new Emblem and Shader.
Someone who buys Destiny: The Taken King and plays it for the first time will be granted "referee" status for one week, during which time they can link with a current player through the Bungie website. Once linked, the Refer-a-Friend quest A Tale of Two Guardians will appear for both players at the Tower's Speaker.
Full details can be found in the Refer-a-Friend FAQ,