Blink is a short range teleport used by Guardians, Fallen and Vex. For Guardians, they are teleported three meters forward, backwards, to the left or right using the corresponding direction on the analogue stick. Not moving the stick will teleport the Guardian upwards.
The Blink ability is usable by Voidwalker Warlocks and Bladedancer Hunters. It replaces the Guardian's other jump abilities. It can be deadly when paired with shotguns. You can confuse the enemy by teleporting towards them and killing them with a shotgun blast.
Only Fallen Captains, Barons, Archons, Kells and Servitors possess a Blink ability. They can actually teleport a lot more than three meters; the maximum distance is currently unknown, although it appears to be around twelve-sixteen meters.
All Vex units possess one type of teleport, the twelve-eighteen meter Blink. They teleport into battle, which is their replacement for spacecraft. This teleport may allow them only to move through space.
List of appearances