The Hajj is the pilgrimage to Mecca, Saudi Arabia. It is one of the largest pilgrimages in the world, and is the fifth pillar of Islam, a religious duty that must be carried out at least once in their lifetime by every able-bodied Muslim who can afford to do so. The Hajj is a demonstration of the solidarity of the Muslim people, and their submission to God (Allah in the Arabic language). The pilgrimage occurs from the 8th to 12th day of Dhu al-Hijjah, the 12th and last month of the Islamic calendar. Because the Islamic calendar is a lunar calendar, eleven days shorter than the Gregorian calendar used in the Western world, the Gregorian date of the Hajj changes from year to year. Ihram is the name given to the special spiritual state in which Muslims live while on the pilgrimage. The Umrah or is a pilgrimage to Mecca, Saudi Arabia, performed by Muslims that can be undertaken at any time of the year. In Arabic, Umrah means "to visit a populated place". As a technical term used in the Sharia, Umrah means to perform Tawaf round the Kaaba and Sa'i between Al-Safa and Al-Marwah, after assuming Ihram (a sacred state), either from a Miqat like Zu 'l-Hulafa, Juhfa, Qarnu 'l-Manāzil, Yalamlam, Zāt-i-'Irq, Ibrahīm Mursīa, or a place in Hill. It is sometimes called the 'minor pilgrimage' or 'lesser pilgrimage', the Hajj being the 'major' pilgrimage and which is compulsory for every able-bodied Muslim who can afford it. The Umrah is not compulsory but highly recommended.