Based on the search results, it is not possible to determine which Islamic holiday Muslims are celebrating today. However, there are two official Islamic holidays: Eid Al-Fitr and Eid Al-Adha. Eid Al-Fitr is celebrated at the end of the month of Ramadan, whereas Eid Al-Adha lands on the 10th day of Dhu al-Hijjah (the final month of the Islamic calendar) . It is worth noting that Shia and Sunni Muslims do not celebrate the same holiday schedule, and that practices vary by nation. Additionally, Friday is considered the holiest day of the week in Islamic tradition and is considered a celebration in itself.