<p><strong>Muslims around the world believe that <a href="http://video.nationalgeographic.com/video/us_ramadanindenver">Ramadan</a>—the ninth month of the Islamic calendar—is the month in which God revealed the Koran to the Prophet Muhammad. During Ramadan, the gates of heaven are open, the gates of hell are closed, and Muslims around the world observe their faith by fasting from sunrise to sunset.</strong></p><p dir="ltr">Muslims fast during Ramadan to purify themselves and to better understand the plight of those who suffer from hunger. Ramadan is also a period during which Muslims strive to abstain from impure thoughts and behavior, to read the Koran and pray, and to think of God.</p><p>The end of Ramadan is celebrated with a three-day Eid al-Fitr (Festival of Fast-Breaking). In this photo, hundreds of thousands of Muslims observe Eid al-Fitr in prayer at the great <a href="http://www.sacred-destinations.com/saudi-arabia/mecca-haram-mosque">al-Masjid al-Haram</a> mosque in Mecca, Saudi Arabia. In just over <a href="http://islam.about.com/od/calendar/fl/When-is-Hajj-2014.htm">two months</a>, a few million &nbsp;Muslims will travel to Mecca for the hajj, or pilgrimage.</p><p><em>—Becky Little</em></p>