Well, everyone knows that Muslims fast for one month every year- the month of Ramadan. The exact dates vary every year- but is the 9th month of the Muslim calendar (they use a lunar calendar- we use the solar one which is why the date changes each year). It is the month the Quran was supposed to be sent down to the prophet Mohammed (while he was walking in the desert) from heaven (via the angel Gabriel). This time is supposed to be a time of religious contemplation- taking time out from the usual concerns of life to focus on God (Allah).
During the daytime- ie all hours between sunrise and sunset, Muslims are supposed to Sawm (fast) They are not supposed to eat, drink, smoke or have sex. Part of the idea being that, while you are hungry and thirsty, you are more likely to be mindful of the hardships of the poor. It also gives you the chance to practice self control and cleanse the body and mind (a detox!) However all the good that is done by fasting is wiped out by various things; During this month, even more than others, Muslims are supposed to aim to refrain from sex, lies, violence, anger, greed envy, sarcasm, lust and gossip.
Those exempt from fasting are children, elderly, ill, pregnant women, and women who are at that time menstruating. Also those in battle or traveling are exempt. If however the reason for missing days is not permanent (eg when a women has her period) that person is supposed to make up the 'lost days' at some point though the year- before the next Ramadan. If however someone breaks the fast by having sex during daytime- they are supposed to make up the days by fasting 60 consecutive days for one days transgression!!!!
At the end of Ramadan there is a huge 3 day feast called Eid el fitr (feast of fast breaking) Food is take in excess and family and friends all meet up and gifts , especially for children, are exchanged ( a lot like our Christmas!)
But before this- on one of the last ten nights of Ramadan- often considered to be the 27th day of Ramadan, there is the night of power (Laylet al-Qadr) - the night is supposed to be when the Quran was given to Mohammed and some Muslims will stay up to pray all this night since it is also supposed to be the night when god decides on the way of the world for the next year (makes up his diary!).