Helmets have been used for centuries to protect heads from injuries. Modern helmets have various innovations - baseball helmets protect ears, motorcycle helmets have face shields and visors, firefighter helmets protect the entire head. New helmet innovations include folding designs for portability, airbag-equipped motorcycle helmets, and helmets that can be opened from the rear for easier removal after accidents. The greatest advancement in helmets since the full-face design is aimed at further reducing head injuries.