Fasting Ramadan is a pillar of Islam. Allah says: the month of Ramadan is the one in which the Quran was revealed, so whoever witnesses the month, let him fast it (2:185). The Prophet ﷺ taught to start fasting on seeing the crescent and to stop on seeing the crescent of Shawwal, and to complete thirty days if the sky is overcast.
1On whom it is obligatory
Every Muslim who is adult, sane and resident, and who is able to fast.
A child is encouraged to fast when able, but it is not obligatory.
2Conditions and the intention
The intention is made in the heart before dawn (see “What breaks the fast” for the views of the schools).
The fast lasts from true dawn to sunset, avoiding food, drink and marital relations.
3The best of it
The Prophet ﷺ reported from Allah that every deed of a son of Adam is for him except fasting, which is for Allah, and He gives its reward. Fasting is a shield.
Eating the pre-dawn meal (suhur), breaking the fast quickly at sunset, with dates and water, giving food to those fasting, and praying Tarawih.
Guarding the tongue, and avoiding lying, arguments and anger.
Where the schools differ
The four Sunni schools agree on the main ruling above and differ in these points. No school is preferred here.
The start of the month. the four schools rely on sighting the crescent, or on completing thirty days. Whether to rely on astronomical calculation, and whether a sighting in one country binds others, is debated among contemporary scholars. Follow the announcement of the authority in your country.
В месяц рамадан был ниспослан Коран - верное руководство для людей, ясные доказательства из верного руководства и различение. Тот из вас, кого застанет этот месяц, должен поститься. А если кто болен или находится в пути, то пусть постится столько же дней в другое время. Аллах желает вам облегчения и не желает вам затруднения. Он желает, чтобы вы довели до конца определенное число дней и возвеличили Аллаха за то, что Он наставил вас на прямой путь. Быть может, вы будете благодарны.
From the Sunnah
Sahih al-Bukhari 1909Authentic collection
The point of the hadith: Start fasting on seeing the crescent, stop on seeing it, and complete thirty days if the sky is cloudy.
Read the Arabic text
حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، حَدَّثَنَا مُحَمَّدُ بْنُ زِيَادٍ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ ـ رضى الله عنه ـ يَقُولُ قَالَ النَّبِيُّ صلى الله عليه وسلم أَوْ قَالَ قَالَ أَبُو الْقَاسِمِ صلى الله عليه وسلم " صُومُوا لِرُؤْيَتِهِ، وَأَفْطِرُوا لِرُؤْيَتِهِ، فَإِنْ غُبِّيَ عَلَيْكُمْ فَأَكْمِلُوا عِدَّةَ شَعْبَانَ ثَلاَثِينَ ".
This is general information, not a fatwa. For your own situation, ask a qualified scholar.
Fiqh questions
Fasting Ramadan: the obligation and its conditions
Fasting Ramadan is a pillar of Islam. Allah says: the month of Ramadan is the one in which the Quran was revealed, so whoever witnesses the month, let him fast it (2:185). The Prophet ﷺ taught to start fasting on seeing the crescent and to stop on seeing the crescent of Shawwal, and to complete thirty days if the sky is overcast.
Is this a fatwa?
No. It is a summary of well-known rulings with their evidence. For your own case, ask a qualified scholar.
What if my school differs from this answer?
Follow the view of the school you follow and the scholar who teaches you. The page lists the differences of the four schools.