Hajj is the Arabic word for pilgrimage, and it is a time where Muslims from all over the world gather at the Kaaba in Makkah for worship. It is a time for togetherness and unity, a time where there is no difference between a king and a beggar. To that end, there is dress code during Hajj that ensures that everyone is the same, just as Muslims believe that every human being, rich or poor, white or black, male or female, is the same in God's eyes.
The dress code for Hajj is part of being in the state of Ihram. This is a state of mind as well as a state of dress for Muslims during Hajj. Before Hajj, Muslims clip their nails, and shave their armpit and pubic hair. Men trim their moustache and apply cologne. Finally, they wear the clothes of Ihram. All this is done at the "Miqat", a designated place on the way to Makkah.
For men, their clothing consists of two pieces of unstitched white cloth. One piece is wrapped around the waist and covers the part of the body from the navel to the ankles. The other piece is draped across the chest leaving one arm exposed and the other arm covered. They must not wear anything that is fitted. A man may not wear a hat or cover his head with cloth, although they may use an umbrella.
The rules for a women's attire during Hajj are more relaxed. A woman must wear loose fitting clothing which covers everything except her hands and face. It can be any color, although it is preferred to wear plain, unpatterned clothes in keeping with the Hajj's message of simplicity and humbleness.
As part of the dress code and state of Ihram, neither a man nor a women is allowed to wear cologne or perfume or use anything scented. Soaps, deodorants, and shampoos must be unscented. They also may not shave, cut their nails, or cut their hair while in the state of Ihram (which lasts the duration of performing Hajj). The state of Ihram also includes holding back one's anger, avoiding fights, avoiding sexual intercourse, marriage, and the hunting and killing of any animal.
If someone violates any of the rules of Ihram, he or she must offer expiation. Expiation is offered in the form of either slaughtering a sheep, fasting for three days, or feeding six needy people.