The trip to Mecca, Saudi Arabia, is known as the Hajj. It is an annual Islamic pilgrimage that all able-bodied Muslims must make at least once in their lives if they can afford it; many Muslims conduct the Hajj alone, while others are accompanied by friends or family, and come join official organizations. Hajj is one of Islam's five pillars. In recent years, about 3 million Muslims have performed Hajj each year.