What is the purpose of a chin strap on a helmet?

The purpose of a chin strap on a helmet is fundamentally to keep the helmet securely on the head. This is crucial in any situation where the helmet is necessary for safety, such as in construction, cycling, or other physically demanding activities. A properly secured helmet helps prevent it from moving or falling off during an impact or sudden movement, significantly enhancing the level of protection it provides. The chin strap ensures that the helmet remains in the correct position, allowing it to absorb shock and protect the wearer’s head effectively.

The other options suggest different functions that are not the primary role of a chin strap. While a helmet may contain small items or contribute to a certain style, these are not its main purposes. Similarly, ventilation is important for comfort but is not relevant to the function of a chin strap, which is strictly for securing the helmet.