Friends

From RWP Wiki

"Friends" is the name Xbox games give to a cross-game contacts list known as a Friends List. Each Friends List is tied to a single Xbox Live gamertag and can contain a maximum of 100 gamertags. Friends Lists allow you to see which of your friends are online, see what game they're playing, send them a message, or - in games that support Online Multiplayer - invite them to play. Bungie Studios' Halo 2 featured an enhanced Friends List that displayed each player's character emblem next to their name.

On the Xbox 360, Friends Lists are part of the Xbox Guide and thus accessible from any game, so "Friends" is no longer part of the feature list on the back of each game's case.