“that they should draw their veils over their bosoms and not display their beauty”
The hijab is the covering a Muslim woman wears for Allah (﷾). For many women it is a daily act of worship, and part of who they are. A woman thinking about Islam does not have to wear it first. Becoming Muslim comes first, and the rest follows step by step.
What the hijab is
It is a scarf over the hair, the neck and the chest, worn with loose clothes that do not show the shape of the body and cannot be seen through. The Qur'an's word for the scarf is khimar; hijab means a screen or a cover. Most scholars hold that a woman may show her face and hands. Some hold that she covers them too, and some women wear the niqab, a veil over the face.
What the Qur'an says
The Qur'an speaks to men first, then to women.
“Say to the believing men that they should lower their gaze and guard their modesty: that will make for greater purity for them: And Allah is well acquainted with all that they do.”
“O Prophet! Tell thy wives and daughters, and the believing women, that they should cast their outer garments over their persons (when abroad): that is most convenient, that they should be known (as such) and not molested.”
Aisha said that when the verse on the head covering came down, the women of Madinah cut cloth from their wraps and covered themselves with it.
Who wears it, and when
A Muslim woman wears the hijab from the time she reaches puberty, when she is with men outside her close family. At home with her husband, her father, her sons, her brothers and the other close relatives the verse names, and with the women it names, she does not need it.
Older women past the age of marriage may set aside their outer garments, though the Qur'an says it is best for them to be modest.
Modesty for men
Modesty is asked of men too. A Muslim man lowers his gaze and dresses modestly, and he does not wear gold or silk.
Wearing it
There is no single style. Any scarf that covers the hair, neck and chest will do, with loose clothes that cover the body. Many women wear a cap underneath so the scarf stays in place, and pin it or wrap it at the side.
Wearing it for the first time can feel hard. The women at a local mosque can help, and dua helps most: ask Allah (﷾) for strength.
Why women wear it
The hijab is worn for Allah (﷾), and the Prophet (ﷺ) said that deeds are judged by their intentions. It is not a sign of being owned. Covering the head was once usual for Christian and Jewish women too, and many nuns still wear the veil.