The ultimate purpose of fasting is to instill God consciousness (taqwā) in human beings.  

Fasting during the month of Ramadan is obligatory on all adult and sane Muslims. The month of Ramadan is the month that the Qur’an was first revealed to the Prophet Muhammad (s). According to the Prophet (s), the month of Ramadan is where the demons or shayātīn are restrained and Muslims are allowed to grow spiritually at an accelerated rate. It is where sins are forgiven, and prayers receive more rewards than they usually do.  

Fasting during the month of Ramadan must begin with the intention or niyya of fasting. Before dawn, one wakes up for suhūr or the predawn breakfast. This ensures that a person can function during the day. Iftār on the other hand is when a person breaks his or her fast at sundown or sunset. 

Fasting is recommended on most days of the year when desires become overwhelming. Fasting helps tame these desires. 

One cannot fast anytime one wants. There are times when fasting is prohibited. Fasting is prohibited when it seriously endangers a person's health, or when a person travels or when it is the Day of Ashura.