More than two million people from around the world are in Mecca for Hajj. Here, they are leaving the tents and making their way to the holy site of Mount Arafat.
The pilgrims form a sea of white as they approach Mount Arafat. There's loads of security to help make sure everything runs smoothly.
The men only wear two white pieces of cloth during the pilgrimage. It's called the Ihram and symbolises purity.
Thousands of people spend the entire day praying at Mount Arafat. It represents how long Muslims' have to wait for the day of judgement.
It's every Muslim's duty to perform Hajj at least once in their life. Even the President of Iran is in Saudi Arabia on his very first pilgrimage.
The Hajj pilgrimage ends on Eid. On this day, Muslims from all over the world pray at the same time.
Everybody takes part in the prayers, even children.