It is to abstain, by the intention of worship, from the things that break the fast, from the true dawn until sunset. Fasting Ramadan is one of the Five Pillars of Islam and one of its obligations.
The obligatory time of fasting the month of Ramadan begins when the beginning of the month is known. This can be done by the sighting of the new moon, being informed of the appearance of the new moon, or by the completion of thirty days of Sha‘ban. So if the new moon is sighted in a country, then all other countries that agree with the country of sighting in seeing the new moon must fast.
It is recommended for one to have Suhoor, strive hard in the acts of worship, such as prayer, reciting Quran, giving voluntary charity, and hastening fast breaking. It also recommended for the fasting person to break his fast with fresh dates; if fresh dates were not available, he would eat (dried) dates; if dried dates were not available, he would have some water; if water were not available, then he would have whatever available of food or beverage.