[Aljazeera] Millions of Muslims from around the world gather annually in Mecca in anticipation of Hajj - the Muslim pilgrimage, which follows the actions of the Prophet Muhammad 1,377 years ago.Taking part in the pilgrimage at least once in one's lifetime is a major obligation for all able-bodied Muslims of financial means, and between two and three million people participate in the six-day ritual every year.
Hajj occurs in the 12th month of the Islamic lunar calendar, called Dhul-Hijjah, between the eighth and 13th days of the month.
While the specific rituals carried out by Muslims today date back to the Prophet Muhammad's "farewell pilgrimage" in 632 AD, travelling to Mecca was a sacred annual rite for Arabian tribes centuries before the advent of Islam.
According to Islamic tradition, the Kaaba - a black silk-clad stone structure at the heart of the Grand Mosque in Mecca - was built by the Prophet Abraham in biblical times.
Hajj is, put simply, complex. There are several different ways of performing it, and numerous schools of Islamic thought, between which lie many scholarly differences. Here is a breakdown of the steps included in performing hajj.