Under the damaged dome of al-Albani Mosque in Khan Younis, families stood on broken stone and dust, raising their voices in takbir, the declaration of god's greatness, to mark the first morning of Eid al-Adha on Friday.

Adha, a period of "communal enjoyment" for Muslims worldwide, has officially arrived. Here's what we've learned about the Islamic holiday.

Adha, the festival of sacrifice by offering prayers in mosques and open spaces before sacrificing animals. (AP video by Muhammad Farooq, Shonal Ganguly and Al Emrun Garjon)