I know that the cosine function is related to the x-coordinate of a point on the unit circle. So, if I want to find the angle whose cosine is 1, I need to look for a point on the unit circle where the x-coordinate is 1. I can visualize the unit circle in my head, and I recall that there is only one such point: the point where the angle is zero radians. Therefore, $\arccos 1 = 0.$ 
Compute $\arccos 1.$  Express your answer in radians.