The Hajj is important because it is one of the five pillars of Islam, and if Muslims have the ability, they are required to perform the Hajj at least once in their lifetimes. They are only excused if they are financially or physically unable to make the pilgrimage.
All adult Muslims, both male and female, are required to perform Hajj, as long as they are of sound mind and body and the performance of the Hajj does not create hardship for their families. During Hajj, males wear only a pair of sandals and the ihram, which consists of two sheets of white cloth, one covering the waist down and the other draped over the shoulder. This symbolizes the shedding of wealth and social differences. Women wear a white dress or their own modest native apparel. Once they are wearing the ihram, pilgrims do not cut their hair, shave, trim their nails, wear perfume, have sex, curse, quarrel, harm animals or plants or carry weapons. Men may not cover their heads, and women may not cover their faces and hands.
Performance of the Hajj dates back to the time of Abraham, and Hagar and Ishmael’s survival in the desert. To perform Hajj, pilgrims must journey to Saudi Arabia. Rituals include walking seven times around the cube-shaped Ka’bah, kissing or touching the Black Stone, running back and forth seven times between Al-Safa and Al-Marwah hills, spending an afternoon on the plain of Arafat, visiting special holy places, sacrificing an animal and throwing stones at three pillars. At the end, the pilgrim circles the Ka’bah once more before leaving Mecca. Once a person has performed Hajj, the title of Hajji is added to his or her name. Source: reference.com