Hijab, which means covering the body from non-mahrams, is one of the essential laws of Islam. There is Hijab in other divine religions, including Zoroastrianism, Judaism and Christianity, with some differences.
Hijab is the wings of the angels of the earth. The woman with hijab has chosen God between herself and her God. 
Quran and its provisions are the basis of unity among all Muslims. Muslim women also have a very influential role in creating and promoting the unity because they can easily affect their children and their husbands.
Click here to see more photos of Muslim woman hijab.