Hijab means veil, curtain, something that protects. In sharia the hijab is a dresscode, that protects the women from looks. When we’re talking about the hijab, we sholud be aware it’s a form of worship, an ibadah. Every ibadah has to be done the way it’s been prescribed.
O Prophet! Tell your wives and your daughters and the women of the believers to draw their cloaks (veils) all over their bodies (i.e. screen themselves completely except the eyes or one eye to see the way). That will be better, that they should be known (as free respectable women) so as not to be annoyed. And Allah is Ever Oft-Forgiving, Most Merciful. Surah 33 verse 59.
Ibn Abbas radiyallahu anhuma said: “Allah has comanded the women to cover themselves completely, only to left one eye open when they need to go outside”.
Some scholars mean that, it isn’t obligatory to cover the eyes and the fists. But they say that it’s better to cover the whole body, and that it’s obligatory when there’re many perverts upon a time.
Like said before, this is a commandment from Allah s.w.t and must be done like it pleases Him azza wa jall