How should a helmet fit to ensure proper protection and safety?

A helmet should fit snugly on the head, with the front edge sitting about one to two finger-widths above the eyebrows. The straps should be adjusted to form a V-shape under the ears, and the chin strap should be snug enough to prevent the helmet from moving around. It's important to ensure that the helmet does not tilt back or slide forward on the head. A properly fitting helmet is crucial for providing maximum protection and safety in case of impact.