Achievement

Achievements are synonymous with Gamerscore on the Xbox 360.
When you unlock an Achievement, you get Gamerscore. To unlock an Achievement, you need to fulfil a specific task.
Achievements vary in difficulty to unlock; some take little to no effort whatsoever, whereas some are nigh impossible to achieve.

Example of an easy Achievement to unlock:

Gears of War: Prison Breakout -
Completed tutorial level on any skill level

Example of a hard Achievement to unlock:

Gears of War: Seriously ... -
Kill 10,000 people in versus ranked match total

45👍 18👎