Ramadhan, holy month

Fasting in the month of Ramadan, like Namaaz (prayers) is a divine command. Allah says in the Holy Quran, "O you who believe! Fasting is prescribed for you, as it was prescribed for those before you, so that you may guard (against evil)." (Al-Baqara, 183)
The Muslim fast means a complete abstention from eating or drinking between daybreak and sunset. The sighting of the thin sickle of the new moon of Ramadan heralds for the Muslim the beginning of a month of glory and of spiritual elevation, when, at Allah's command, he voluntarily and of his own free will, denies himself between day-break and sunset, the blessing of food and drink, and surrenders himself up wholly to Allah, observing the same abstention throughout the whole month in his thoughts, his speech, his behavior, his every act.
For this month, for the Muslim, means the triumph of the spiritual and the pure in his nature over all the grossness and carnation, which is an inevitable component of our human make-up. The Holy Prophet Muhammad (SAW) in the following words beautifully explains the actual significance of the fast:
"One who, while fasting, does not guard his tongue from telling lies, does not refrain from doing bad deeds, is not respecting his fast and Allah does not approve of mere abstention from food". When you are keeping fast, you should not speak ill of anybody, nor should you be boisterous and noisy. If anybody speaks ill of you or tries to pick a quarrel with you return him not, but say unto him that you are fasting.
Source: tebyan.net

Related Links:
Benefits of Fasting
Ramadan in Iran