Ramadan will last a whole month. It goes by the moon. The new moon brings Ramadan and the new moon takes it out.
So as long as it is Ramadan the Muslim "Must" fast.
The Islamic fast is no food, no water, no nothing by mouth and no sex as long as it is daylight.
When the sun goes down we break our fast.
At dusk or as we call it mughrib we break the fast with water or traditional dates. Then we pray the dusk prayer. Muslims pray 5x's a day. Then we eat the meal that breaks the fast.
During Ramadan there are extra prayers. So from( right now at this time of year) about 10pm until 12 am we pray and read Quran.
Ramadan is the time of worship.
Quran verses about fasting:
2:183 O you who believe, fasting has been decreed for you as it was decreed for those before you, perhaps you may be righteous.
2:184 A few number of days; however, if any of you is ill or traveling, then the same number from different days; and as for those who can do so but with difficulty, they may redeem by feeding the needy. And whoever does good voluntarily, then it is better for him. And if you fast it is better for you if only you knew.
2:185 A month of aspiration, in which the Quran was revealed; as a guide to the people and clarities from the guidance and the Criterion. Therefore, whoever of you witnesses the month, then let him fast therein. And whoever is ill or traveling, then the same number from different days. God wants to bring you ease and not to bring you hardship; and so that you may complete the count, and glorify God for what He has guided you, that you may be thankful.
2:187 It has been made lawful for you during the night of fasting to approach your women sexually. They are a garment for you and you are a garment for them. God knows that you used to betray your souls so He has accepted your repentance, and forgiven you; now you may approach them and seek what God has written for you. And you may eat and drink until the white thread is distinct from the black thread of dawn; then you shall complete the fast until night; and do not approach them while you are devoted in the temples. These are the boundaries of God, so do not transgress them. It is thus that God clarifies His revelations to the people who they may be righteous.
33:35 Surely, the submitting males, and the submitting females, the believing males, and the believing females, the dutiful males, and the dutiful females, the truthful males, and the truthful females, the patient males, and the patient females, the humble males, and the humble females, the charitable males, and the charitable females, the fasting males, and the fasting females, the males who keep covered their private parts, and the females who similarly keep covered, and the males who commemorate God frequently, and the commemorating females; God has prepared for them a forgiveness and a great recompense