Hajj is an annual Islamic pilgrimage to the holy city of Mecca in Saudi Arabia that is a mandatory religious duty for Muslims at least once in their lifetime, provided they are physically and financially able to do so.

The pilgrimage takes place during the Islamic month of Dhu al-Hijjah and involves a series of rituals, such as the wearing of the ihram (a white, seamless garment), the circumambulation of the Kaaba (the most sacred site in Islam), and the standing at the plain of Arafat. The pilgrimage culminates with the Eid al-Adha celebration, which commemorates the willingness of Prophet Ibrahim (Abraham) to sacrifice his son in obedience to Allah's command.

Hajj is considered one of the five pillars of Islam and is a significant act of worship that brings together Muslims from all over the world in a spirit of unity and devotion to Allah. The pilgrimage is also an opportunity for Muslims to reflect on their faith, seek forgiveness, and strengthen their relationship with Allah.

Overall, Hajj is a fundamental part of Islamic teachings, emphasizing the importance of spiritual purity, submission to Allah, and unity among Muslims.