A helmet is a safety device worn on the head to protect against impact, injury, or trauma during activities such as riding motorcycles and bicycles, playing contact sports, or working in hazardous environments like construction sites. Typically made from hard outer shells (such as ABS or polycarbonate plastic) and inner foam padding (like EPS), helmets are designed to absorb shock and distribute impact force. Many helmets also include features like adjustable straps, ventilation, visors, and reflective elements for added comfort and safety. They are crucial for reducing the risk of serious head injuries and are often required by law in many regions for specific activities. Helmets come in various types, including full face, open face, modular, and sports specific versions, each suited for different needs.