The hajj is the annual pilgrimage to the Saudi Arabian city of Makka (often spelled Mecca), which occurs between the 7th and 12th (or sometimes the 13th) of Dhu al-Hijjah--the last month of the Islamic calendar. The comparable dates for the hajj in the Gregorian calendar change from year to year because the Islamic calendar is shorter than the Gregorian. It's a mandatory duty for all Muslims to complete the pilgrimage once in their lifetime, provided they are physically and financially able to do so.
The hajj is the single largest annual gathering of human beings on earth, and there are many holy rituals associated with the pilgrimage--including how one dresses to complete the hajj. For a pilgrim traveling to Makka for the hajj, at a point about ten km (six miles) from the city, he or she pauses to change into special clothes that symbolize an attitude of purification and humbleness.
To complete the pilgrimage, Muslims shed all signs of their wealth and societal distinctions by donning simple white garments, commonly called ihram clothing. The required pilgrimage dress for men is two white cloths without seams or stitches, one of which covers the body from the waist down and one that is gathered around the shoulder. The sandals a pilgrim wears are required to be constructed without stitches, as well. Before donning the ihram clothing, men shave their heads and trim their beards and nails.
Women usually wear a simple white dress and headscarf, or their own native dress, and they often omit face coverings. They also clean themselves, and may remove a single lock of hair.
The ihram clothing is a symbol of purity and equality, and signifies that the pilgrim is in a state of devotion. The goal is to eliminate all class distinctions so that all pilgrims present themselves as equal in the eyes of God.
For this last phase of the pilgrimage, men and women conclude the hajj together, without separation--there are not even gender distinctions between pilgrims at this point. Cleanliness is regarded with great importance during hajj; if the ihram clothing becomes soiled, the hajj is regarded as invalid.
The word ihram also refers to the personal state of sacred purification that pilgrims must be in when they conclude the hajj. This sacred state is symbolized by the ihram clothing, so that the word is used to refer to both the clothing and the sacred mental state adopted during the hajj. During ihram, there are other requirements that Muslims follow in order to focus their energy on spiritual devotion. Harming any living thing is forbidden--no hunting, fighting or vulgar language is permitted, and no weapons may be carried. Vanity is discouraged, and Muslims approach pilgrimage by assuming a state that is as natural as possible: excessive perfumes and colognes are not used; hair and fingernails are left in their natural state without trimming or cutting. Marital relations are also suspended during this time, and marriage proposals or weddings are delayed until after the pilgrimage experience is completed.
All scholarly or business conversation is suspended during the hajj, in order to focus one's attention on God.