It is obligatory on every Muslim to go to the Kaaba (House of God) once in his life, and perform a series of specific acts.
Kaaba is located in Mecca, Saudi Arabia. The rituals of the Hajj are the same in both Sunnis and Shiites. The person who goes to Hajj is called Hajji.
Except for the obligatory Hajj: the duration of the ceremony is three days, we also have a kind of recommended Hajj, which is known as Umrah Hajj, and it is rewarding to perform it.