Ramadan (Arabic: رمضان) (also written Ramazan, Ramzan, Ramadhan, Ramdan, Ramadaan) is the ninth month of the Islamic calendar. It is the Islamic month of fasting, in which participating Muslims refrain from eating, drinking, smoking, and indulging in anything that is in excess or ill-natured; from dawn until dusk .
Fasting is meant to teach the Muslim patience, modesty and spirituality. Ramaḍān is a time to fast for the sake of Allah, and to offer more prayer than usual. During Ramaḍān, Muslims ask forgiveness for past sins, pray for guidance and help in refraining from everyday evils, and try to purify themselves through self-restraint and good deeds.
In the Qu'ran, God proclaims that "fasting has been written down (as obligatory) upon you, as it was upon those before you
Laylat al-Qadr, considered the most holy night of the year, is the night in which the Qur'an was revealed to Muhammad, the "Night of the Power". Muslims believe it to have occurred on an odd-numbered night during the last 10 days of Ramaḍān, either the night of the 21st, 23rd, 25th, 27th or 29th (in Sunni thought) or the 19th, 21st or 23rd (in Shi'a thought).
Ramaḍān ends with Eid ul-Fitr on the 1 of Shawwal, with much celebration and feasts. During the month following Ramaḍān, called Shawwal, Muslims are encouraged to fast for a further six days, known as as-Sitta al-Bīḍ, or "the white six." When fasting is over, Muslims go to Mosques in nice clothes to pray the first Eid prayer. They give out presents to the young ones and greet their friends and families. They then thank God for what He has given them.
The most prominent event of this month is fasting. Every day during the month of Ramadan, Muslims around the world get up before dawn to eat Sahur, the pre-dawn meal, then they perform the fajr prayer. They have to stop eating and drinking before the call for prayer starts until the fourth prayer of the day, Maghrib. Muslims may continue to eat and drink after the sun has set until the next morning's fajr prayer call. Then the process starts all over.
Source : http://en.wikipedia.org/wiki/Ramadan