With headshots being instant kills, and even a couple of body shots having the same effect, leaning around corners or peeking through openings is crucial to your survival.
Here's our guide to leaning, which should hopefully stop your enemies turning you into swiss cheese.
Rainbow Six Siege: How to lean
If you're playing with a mouse and keyboard, you'll need to aim-down-sights.
With your weapon raised, press 'E' or 'Q' to lean left or right respectively.
Xbox One and PS4
Leaning on console is nice and straightforward. Regardless of which platform you're on, simply aim-down-sights.
Once you're scoped, click the left thumbstick to lean left, or the right thumbstick to lean right.
Nice and simple.