While there is also another related question on the website, my question is however different:
In many countries, Muslim women don't cover their face and palms, although they cover their hair, ears, neck, the parts of hand higher than wrist, and their body by Hijab.
There are also some Islamic countries that women cover their face with Hijab. Is it part of Islam or it's just a cultural issue of that countries? Is it a must? And if it is not a must in Islam, doesn't it limit the social activity of women in that countries?