What is white knuckle?

White knuckle refers to the sensation of gripping an object so tightly that the knuckles turn white due to the pressure. This can be caused by fear, anxiety, stress, or excitement. The term can also refer to the experience of engaging in intense or dangerous activities that induce white knuckle gripping, such as extreme sports or high-speed driving. The phrase can also be used metaphorically to describe a situation that is tense or nerve-wracking, such as a stressful job or an important presentation.