Short answer
Purdah is a Persian and Urdu word meaning curtain. In South Asia it is the everyday name for the Islamic rules of hijab: a woman covering herself before non-mahram men, and men and women keeping apart where there is no need to mix. In the Hanafi teaching of the subcontinent it usually includes covering the face.
The substance of purdah is fard: covering the awrah before non-mahram men and avoiding khalwah (being alone with a non-mahram) and needless mixing. The Hanafi scholars of the subcontinent also teach covering the face before non-mahram men in our time. Customs that go beyond this, such as keeping a woman from all education or medical care, are not part of the Shariah.
The four schools agree on this.
Explanation
The word comes from Persian pardah, a curtain or screen. In Urdu, Bengali and Hindi it became the usual word for what Arabic calls hijab. When a South Asian family says it "keeps purdah", it means the women cover in front of men who are not mahram, and the household keeps men and women apart where it can.
The roots are in the Quran. Women are told to cover their adornment and draw their head covers over their chests. They are told to stay in their homes and not to display themselves as in the days of ignorance. The Companions were told to ask the Prophet's ﷺ wives for things from behind a screen, the literal pardah, because it is purer for the hearts of both sides.
Purdah in the Hanafi teaching has three layers:
- Covering the body: everything except the face and hands is awrah before non-mahram men. The feet are not awrah in prayer on the relied-upon Hanafi view; outside prayer, covering them is the safer course. See awrah for men and women.
- Covering the face: later Hanafi jurists barred a young woman from showing her face to non-mahram men because of fitnah. See is niqab compulsory.
- Distance: no khalwah, and no mixing without need. See is free mixing haram.
What purdah is not. It is not a ban on leaving the house. Women in the time of the Prophet ﷺ went out for their needs, prayed in the masjid, nursed the wounded and traded. Keeping a girl from school, a woman from a doctor, or a wife from her own family is not purdah but injustice. See education for women and can women work.
For the garments themselves, see hijab, niqab, burqa and abaya.
The evidence
Quran, Surah Al-Ahzaab 33:53
يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تَدْخُلُوا۟ بُيُوتَ ٱلنَّبِىِّ إِلَّآ أَن يُؤْذَنَ لَكُمْ إِلَىٰ طَعَامٍ غَيْرَ نَٰظِرِينَ إِنَىٰهُ وَلَٰكِنْ إِذَا دُعِيتُمْ فَٱدْخُلُوا۟ فَإِذَا طَعِمْتُمْ فَٱنتَشِرُوا۟ وَلَا مُسْتَـْٔنِسِينَ لِحَدِيثٍ ۚ إِنَّ ذَٰلِكُمْ كَانَ يُؤْذِى ٱلنَّبِىَّ فَيَسْتَحْىِۦ مِنكُمْ ۖ وَٱللَّهُ لَا يَسْتَحْىِۦ مِنَ ٱلْحَقِّ ۚ وَإِذَا سَأَلْتُمُوهُنَّ مَتَٰعًۭا فَسْـَٔلُوهُنَّ مِن وَرَآءِ حِجَابٍۢ ۚ ذَٰلِكُمْ أَطْهَرُ لِقُلُوبِكُمْ وَقُلُوبِهِنَّ ۚ وَمَا كَانَ لَكُمْ أَن تُؤْذُوا۟ رَسُولَ ٱللَّهِ وَلَآ أَن تَنكِحُوٓا۟ أَزْوَٰجَهُۥ مِنۢ بَعْدِهِۦٓ أَبَدًا ۚ إِنَّ ذَٰلِكُمْ كَانَ عِندَ ٱللَّهِ عَظِيمًا ﴿٥٣﴾
O you who have believed, do not enter the houses of the Prophet except when you are permitted for a meal, without awaiting its readiness. But when you are invited, then enter; and when you have eaten, disperse without seeking to remain for conversation. Indeed, that [behavior] was troubling the Prophet, and he is shy of [dismissing] you. But Allah is not shy of the truth. And when you ask [his wives] for something, ask them from behind a partition. That is purer for your hearts and their hearts. And it is not [conceivable or lawful] for you to harm the Messenger of Allah or to marry his wives after him, ever. Indeed, that would be in the sight of Allah an enormity.
The screen between men and the Prophet's wives is the literal meaning of purdah, and the verse calls it purer for the hearts.
Quran, Surah Al-Ahzaab 33:33
وَقَرْنَ فِى بُيُوتِكُنَّ وَلَا تَبَرَّجْنَ تَبَرُّجَ ٱلْجَٰهِلِيَّةِ ٱلْأُولَىٰ ۖ وَأَقِمْنَ ٱلصَّلَوٰةَ وَءَاتِينَ ٱلزَّكَوٰةَ وَأَطِعْنَ ٱللَّهَ وَرَسُولَهُۥٓ ۚ إِنَّمَا يُرِيدُ ٱللَّهُ لِيُذْهِبَ عَنكُمُ ٱلرِّجْسَ أَهْلَ ٱلْبَيْتِ وَيُطَهِّرَكُمْ تَطْهِيرًۭا ﴿٣٣﴾
And abide in your houses and do not display yourselves as [was] the display of the former times of ignorance. And establish prayer and give zakah and obey Allah and His Messenger. Allah intends only to remove from you the impurity [of sin], O people of the [Prophet's] household, and to purify you with [extensive] purification.
Tells women not to make a display of themselves as in the time of ignorance.
Quran, Surah An-Noor 24:31
وَقُل لِّلْمُؤْمِنَٰتِ يَغْضُضْنَ مِنْ أَبْصَٰرِهِنَّ وَيَحْفَظْنَ فُرُوجَهُنَّ وَلَا يُبْدِينَ زِينَتَهُنَّ إِلَّا مَا ظَهَرَ مِنْهَا ۖ وَلْيَضْرِبْنَ بِخُمُرِهِنَّ عَلَىٰ جُيُوبِهِنَّ ۖ وَلَا يُبْدِينَ زِينَتَهُنَّ إِلَّا لِبُعُولَتِهِنَّ أَوْ ءَابَآئِهِنَّ أَوْ ءَابَآءِ بُعُولَتِهِنَّ أَوْ أَبْنَآئِهِنَّ أَوْ أَبْنَآءِ بُعُولَتِهِنَّ أَوْ إِخْوَٰنِهِنَّ أَوْ بَنِىٓ إِخْوَٰنِهِنَّ أَوْ بَنِىٓ أَخَوَٰتِهِنَّ أَوْ نِسَآئِهِنَّ أَوْ مَا مَلَكَتْ أَيْمَٰنُهُنَّ أَوِ ٱلتَّٰبِعِينَ غَيْرِ أُو۟لِى ٱلْإِرْبَةِ مِنَ ٱلرِّجَالِ أَوِ ٱلطِّفْلِ ٱلَّذِينَ لَمْ يَظْهَرُوا۟ عَلَىٰ عَوْرَٰتِ ٱلنِّسَآءِ ۖ وَلَا يَضْرِبْنَ بِأَرْجُلِهِنَّ لِيُعْلَمَ مَا يُخْفِينَ مِن زِينَتِهِنَّ ۚ وَتُوبُوٓا۟ إِلَى ٱللَّهِ جَمِيعًا أَيُّهَ ٱلْمُؤْمِنُونَ لَعَلَّكُمْ تُفْلِحُونَ ﴿٣١﴾
And tell the believing women to reduce [some] of their vision and guard their private parts and not expose their adornment except that which [necessarily] appears thereof and to wrap [a portion of] their headcovers over their chests and not expose their adornment except to their husbands, their fathers, their husbands' fathers, their sons, their husbands' sons, their brothers, their brothers' sons, their sisters' sons, their women, that which their right hands possess, or those male attendants having no physical desire, or children who are not yet aware of the private aspects of women. And let them not stamp their feet to make known what they conceal of their adornment. And turn to Allah in repentance, all of you, O believers, that you might succeed.
Commands believing women to draw their head covers over their chests and not to show their adornment except to close family.
Jami' at-Tirmidhi 1173
Graded sahih... المرأة عورة فإذا خرجت استشرفها الشيطان ...
"A woman is awrah, and when she goes out, Shaytan makes her the focus of looks."
The basis for covering when a woman goes out.
Sahih al-Bukhari 4795
Sahih... قد أذن لكن أن تخرجن لحاجتكن ...
"You have been permitted to go out for your needs."
Purdah does not mean never leaving the house.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Salah, chapter on the conditions of prayer. A young woman is barred from uncovering her face among men, out of fear of fitnah.
- al-Hidaya, Kitab al-Karahiyya, chapter on looking and touching. Sets out what of a woman may be seen by a non-mahram man.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.