Fasting is obligatory during the month of Ramadan and it is a way of showing our obedience and submission to our creator by regulating our hunger.
Ramadan is a yearly training session to implement this wisdom and gain closeness to Allah. It is mentioned often that if one can that if a person can control his desire of hunger, he could discipline all other physical cravings. Fasting is obligatory on all Muslims with the following exceptions: Young, sick, travelers on a journey and menstruating women.
However, all missed fasts should be made up. Fasting period begin at dawn and ends at sunset. During this period, all food and all liquids including water is forbidden. It is recommended that a predawn meal should be taken before the fast begins. This meal provides a source of blessings and nourishment. Fasting should be broken at sunset with dates, also a person should not have a physical connection with his or her mate during fasting day.

Allah (SWT) said in the holy Quran about Ramadan:

2-183 "O you who believe! fasting is prescribed for you, as it was prescribed for those before you, so that you may guard (against evil)."

2-184 "For a certain number of days; but whoever among you is sick or on a journey, then (he shall fast) a (like) number of other days; and those who are not able to do it may effect a redemption by feeding a poor man; so whoever does good spontaneously it is better for him; and that you fast is better for you if you know."

2-185 "The month of Ramazan is that in which the Quran was revealed, a guidance to humans and clear proofs of the guidance and the distinction; therefore whoever of you is present in the month, he shall fast therein, and whoever is sick or upon a journey, then (he shall fast) a (like) number of other days; Allah desires ease for you, and He does not desire for you difficulty, and (He desires) that you should complete the number and that you should exalt the greatness of Allah for His having guided you and that you may give thanks."

2-186 "And when My servants ask you concerning Me, then surely I am very near; I answer the prayer of the suppliant when he calls on Me, so they should answer My call and believe in Me that they may walk in the right way."

2-187 "It is made lawful to you to go into your wives on the night of the fast; they are an apparel for you and you are an apparel for them; Allah knew that you acted unfaithfully to yourselves, so He has turned to you (mercifully) and removed from you (this burden); so now be in contact with them and seek what Allah has ordained for you, and eat and drink until the whiteness of the day becomes distinct from the blackness of the night at dawn, then complete the fast till night, and have not contact with them while you keep to the mosques; these are the limits of Allah, so do not go near them. Thus does Allah make clear His revelations for humans that they may guard (against evil)."