The Hijab is Modesty 2 :

Islam promotes modesty and decency and seeks to minimise immorality within society.The Hijab,amongst other things, helps attain this goal.“Say to the believing men that they should lower their gaze and guard their modesty:That is purer for them;and Allah is well acquainted with all that they do.And say to the believing women that they should lower their gaze and guard their modesty.