Hajj refers to a Muslim’s pilgrimage to Mecca and is one of the five pillars of Islam. At least once in his or her lifetime, each Muslim is expected to undertake this pilgrimage the sacred city of Islam. This holy journey is called the hajj in Arabic. While a visit to Mecca is beneficial at any time of the year, it must take place during the month of Dhu al-Hijja (the last month of the Islamic year) to fulfill the requirements of the hajj.
As with the sawm (fasting), exceptions are made for those who are physically or financially unable to fulfill this obligation, and one is actually commanded not to make the hajj if to do so would cause hardship for his or her family. However, those unable to go themselves may fulfill their obligation by sending someone in their stead.