Headwear, also known as Headgear or Headdress,  is the name given to any element of clothing which is worn on one's head. It serves variety of purposes and is used
o    as protection (against impact, cold, heat, rain and other precipitation, glare,   sunburn, sunstroke, dust, contaminants, etc.)
o    to keep hair contained or tidy
o    as decoration or fashion     
o    for religious purposes
o    for medical purposes
o    to indicate modesty; social convention   
o    as distinction or identification of office