Journey to Mecca, also known as the Hajj, is an Islamic pilgrimage to the holy city of Mecca in Saudi Arabia. The Hajj is one of the five pillars of Islam and is a mandatory religious duty for Muslims who are able to undertake the journey. The term 'Hajj' is derived from the Arabic word meaning 'to set out for a place'. The term 'Hadj' is an alternative spelling of the same word, while 'Hajj' is the plural form. All three terms refer to the same pilgrimage.