Hajj
Ariel view of the Kaaba at the Grand mosque in Mecca, Saudi Arabia, Sept. 6, 2016. REUTERS/Ahmed Jadallah

The annual pilgrimage for Muslims called Hajj, which happens during the eighth and the 12th of the month of Dhul Hijjah — the last month of the Islamic calendar — is underway when millions of Muslims travel to the Saudi Arabian city of Mecca. This year the gathering, which is one of the Five Pillars of Islam, officially began on the evening of Aug. 30 and ends on the evening of Sept. 4.

"There has been a confirmed sighting of the crescent of Dhu al-Hijjah. Tomorrow, Wednesday, will be the first day of Dhu al-Hijjah," Saudi Arabia's High Judicial Court said Tuesday. The month of Hajj, however, began on Aug. 23.

Eid al Adha, also known as the Feast of Sacrifice, that represents the end of Hajj, will be marked in Saudi Arabia and other Muslim majority nations on Sept. 1, but the last day for sacrifice will be Sept. 4.

hajj mecca
Muslims touch and pray at the door of the Kaaba and touch and kiss the al-Hajr al-Aswad "Black Stone" during their Umrah Mawlid al-Nabawi "Birthday of Prophet Mohammad" in the holy city of Mecca, Saudi Arabia, Jan. 18, 2016. REUTERS/AMR ABDALLAH DALSH

To watch a live stream from Mecca, scroll down to the end of the article to see the live video feed.

Hajj facts:

1. Muslims are required to make the journey at least once in their lifetime, and the only people exempted from the travel are those who cannot physically endure the journey or are not financially capable.

2. There isn’t any gender segregation at Hajj, unlike other Muslim rites.

3. Saudi Arabia began to expand the Grand Mosque in Mecca due to the large footfall.

Hajj 2014
Muslim pilgrims from all over the world pray around the holy Kaaba at the Grand Mosque during the annual Hajj pilgrimage in Mecca, Saudi Arabia, Sept. 27, 2014. Reuters/Muhammad Hamed

4. Other Hajj rituals include “tawaf,” or the circling of the large Kaaba, and "Sa’ee," where pilgrims walk between two hills – Marwah and Safa – seven times.

5. After Muslims reach Mina, located just outside of Mecca, a ritual called the "stoning of the devil" takes place.

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Muslim pilgrims arrive to throw pebbles at pillars during the stoning of Satan ritual, in Mina near the holy city of Mecca, Sept. 24, 2015. Getty Images

6. Thousands of people have died over the years during Hajj due to stampede.

7. Some 3.7 million people participate for Hajj every year.

8. In 2015, a crane used for renovation work inside the Grand Mosque in Mecca fell over and tragically killed over 100 people.

9. Hundreds of pilgrims were killed during a stampede in Mina near the holy city of Mecca Sept. 24, 2015. That year, Saudi Arabian officials said it received around 2 million pilgrims from more than 180 countries for the annual Islamic pilgrimage to Mecca.

Hajj Stampede
Saudi emergency personnel and hajj pilgrims load a wounded person into an ambulance at the site of a stampede in the holy city of Mecca, Sept. 24, 2015. STR/AFP/Getty Images

10. The Saudi government has been criticized by many Muslims for commercializing and seeking to cash in on the pilgrimage.

What is Eid Al Adha?

Millions of Muslims across the globe celebrate the day as a reminder of the time when Prophet Ibrahim was about to sacrifice his son at God’s command. But when Ibrahim was on the verge of making the sacrifice, God spared his life, replacing him with an animal. This day symbolizes Ibrahim’s devotion to "Allah" (God). During Eid Al Adha, Muslims with the financial means sacrifice an animal such as a sheep, goat or cow.