Tilt & turn windows are unique because of their multi-functional handle and locking mechanism. When handle of a tilt-and-turn is in the downward position, the window is shut is and locked. But, if you rotate the handle 90 degrees, you can then swing the window fully open.

Even more interestingly, when you push the window back into place, rotate the handle another 90 degrees so it points up, and then pull it back down toward you the window can lock into place after opening a few inches, resting at an angle. This not only allows for positive airflow, but it also means that you can enjoy a natural breeze while still knowing you have the added security of a locked window. 

Tilt & turn window systems, unlike regular hung windows, have multi-point locking mechanisms that you can feel click into place, providing further security and a completely air-tight weather seal.