You are asking about hijab, and about men shaking hands with women, and about looking at them as well?

Question:
May Allah reward you with good, and may He do you good. You are asking about hijab, and about men shaking hands with women, and about looking at them as well. May Allah reward you with good.

Answer:
Hijab is obligatory for women, and it means that a woman covers her entire body from men who are not her mahram (a relative one may not marry). This is hijab: that a woman covers her whole body from men who are not her mahram, including the face and the hands, and the rest of the body. She covers it with something that conceals it and covers it entirely, and it must be loose, not tight, and it must not contain adornment that tempts people. It should be an ordinary garment and must not contain perfume. When a woman goes out of her house, she does not apply perfume, and she does not wear clothes of adornment, and she does not wear tight clothes or short clothes. All of this undermines hijab. The Prophet (peace and blessings be upon him) said: "Two categories of the people of the Fire whom I have not seen" These women are negligent in covering and in hijab. Even if they have clothes on, their clothes do not cover their 'awrah (the part of the body that must be covered). There is nakedness in them. She is clothed in one sense, but naked in another sense. They are clothed yet naked. It is obligatory for Muslim women to be cautious about being lax in the matter of hijab. As for the rest of the question, which is also about hijab and shaking hands with men.
Women may not shake hands with men who are not their mahram; because the hand of the Prophet (peace and blessings be upon him) did not touch the hand of a woman who was not lawful for him, as came in the hadith, not by shaking hands; because of what is in shaking hands of stirring up fitnah (trial, discord or temptation), and the woman’s closeness to the man, which stirs up fitnah. Even if this woman is one of his relatives who are not his mahram, such as his cousin’s daughter, or his maternal cousin’s daughter, or his wife’s sister, or something similar, it is not permissible for a man to shake hands with a woman who is not lawful for him.