Islam has relatively few holidays compared to most other religions; nevertheless, sacred days and times are very important to Muslims.
When holidays are being observed, it is common for routine social activities, such as work and commerce, to stop temporarily out of respect for the person or event being remembered.
Most Islamic holidays either commemorate events in the life of the prophet Muhammad or are special days founded by him.
Traditionally, Muslims observe two major festivals ('Id Al-Fitr and 'Id Al-Adha) and one month of daytime fasting (Ramadan). There is also a day of voluntary fasting: 'Ashura, which is also an important Shiite festival. (Also compare: Sunni and Shia Muslims.)
The popular festival of Mawlid an-Nabi celebrates the birthday of the prophet Muhammad, but is frowned upon as an idolatrous innovation by conservative Muslims.