Ramadan (Arabic: رمضان Ramaḍān, Arabic pronunciation: [rɑmɑˈdˤɑːn]) (also Ramadhan, Ramadaan, Ramazan) is the ninth month of the Islamic calendar, which lasts 29 to 30 days. It is the Islamic month of fasting, in which participating Muslims refrain from eating and drinking during daylight hours and is intended to teach Muslims about patience, spirituality, humility and submissiveness to God. Muslims fast for the sake of God (Arabic: الله, trans: Allah) and to offer more prayer than usual. Compared to the solar calendar, the dates of Ramadan vary, moving backwards by about eleven days each year depending on the moon; thus, a person will have fasted every day of the calendar year in 34 years' time. Muslims believe Ramadan to be an auspicious month for the revelations of God to humankind, being the month in which the first verses of the Qur'an were revealed to the Islamic prophet, Muhammad peace be upon him.
Origins of Ramadan
The word Ramadan is derived from an Arabic root rmḍ, as in words like "ramiḍa" or "ar-ramaḍ" denoting intense heat, scorched ground and shortness of rations. Ramadan, as a name for the month, is of Islamic origin. Prior to Islam and the exclusion of intercalary days from the Islamic calendar, the name of the month was Natiq and the month fell in the warm season. The word was thus chosen as it well represented the original climate of the month and the physiological conditions precipitated from fasting. In the Qur'an, God proclaims that "fasting has been written down (as obligatory) upon you, as it was upon those before you". According to a hadith, it might refer to the Jewish practice of fasting on Yom Kippur.
The Beginning of Ramadan
Hilāl (the crescent) is typically a day (or more) after the astronomical new moon. Since the new moon indicates the beginning of the new month, Muslims can usually safely estimate the beginning of Ramadan.
There are many disagreements each year however, on when Ramadan starts. This stems from the tradition to sight the moon with the naked eye and as such there are differences for countries on opposite sides of the globe. More recently however, some Muslims are leaning towards using astronomical calculations to avoid this confusion.
For the year of 1432 Hijri, the first day of Ramadan was determined to be August 1, 2011.
Practices during Ramadan
The month of Ramadan is the one in which the Qur'an was sent down - right Guidance to mankind, and clear signs of Guidance and Distinction of truth from falsehood. Those among you who witness it, let him fast therein. Whoever is sick or on a journey, then a number of other days. God desires ease for you, and desires not hardship. Thus may you fulfil the number of days assigned, magnify God for having guided you, and perhaps you will be thankful.
Ayah 185, Sura 2 (Al-Baqara), translation by Tarif Khalidi see:
Ramadan is a time of reflecting, believing and worshiping God. Muslims are expected to put more effort into following the teachings of Islam and to avoid obscene and irreligious sights and sounds. Sexual intercourse among spouse is allowed after one has ended the fast. During fasting intercourse is prohibited as well as eating and drinking, one is also encouraged to resist all temptations while you are fasting. Purity of both thoughts and actions is important. The act of fasting is said to redirect the heart away from worldly activities, its purpose being to cleanse the inner soul and free it from harm. It also teaches Muslims to practice self-discipline, self-control, sacrifice, and empathy for those who are less fortunate; thus encouraging actions of generosity and charity (Zakat).
Muslims should start observing the fasting ritual upon reaching the age of puberty, so long as they are healthy, sane and have no disabilities or illnesses. The elderly, the chronically ill, and the mentally ill are exempt from fasting, although the first two groups must endeavor to feed the poor in place of their missed fasting. Also exempt are pregnant women if they believe it would be harmful to them or the unborn baby, women during the period of their menstruation, and women nursing their newborns. A difference of opinion exists among Islamic scholars as to whether this last group must make up the days they miss at a later date, or feed poor people as a recompense for days missed. While fasting is not considered compulsory in childhood, many children endeavour to complete as many fasts as possible as practice for later life. Lastly, those traveling (musaafir) are exempt, but must make up the days they miss. More specifically, Twelver Shī‘ah define those who travel more than 14 mi (23 km) in a day as exempt.
Prayer and reading of the Qur'an
In addition to fasting, Muslims are encouraged to read the entire Qur'an. Some Muslims perform the recitation of the entire Qur'an by means of special prayers, called Tarawih, which are held in the mosques every night of the month, during which a whole section of the Qur'an (Juz', which is 1/30 of the Qur'an) is recited. Therefore the entire Qur'an would be completed at the end of the month.
Ramadan is also a time when Muslims are to slow down from worldly affairs and focus on self-reformation, spiritual cleansing and enlightenment; this is to establish a link between themselves and God through prayer, supplication, charity, good deeds, kindness and helping others. Since it is a festival of giving and sharing, Muslims prepare special foods and buy gifts for their family and friends and for giving to the poor and needy who cannot afford it; this can involve buying new clothes, shoes and other items of need. There is also a social aspect involving the preparation of special foods and inviting people for Iftar.
Iftar in Sultan Ahmed Mosque in Is Istanbul,Turkey
Muslims all around the world will abstain from food and drink, through fasting, from dawn to sunset. At sunset, the family will gather the fast-breaking meal known as Iftar. The meal starts with the eating of a date — just as Prophet Muhammad peace be upon him used to do. Then it's time for the Maghrib prayer, which is the fourth of the five daily prayers, after which the main meal is served. 
Over time, Iftar has grown into banquet festivals. This is a time of fellowship with families, friends and surrounding communities, but may also occupy larger spaces at mosques or banquet halls, where a hundred or more may gather at a time.
Most markets close down during evening prayers and the Iftar meal, but then re-open and stay open for a good part of the night. Muslims can be seen shopping, eating, spending time with their friends and family during the evening hours. In many Muslim countries, this can last late into the evening, to early morning. However, if they try to attend to business as usual, it can become a time of personal trials, fasting without coffee or water.
Charity is very important in Islam, and even more so during Ramadhan. According to tradition, Ramadhan is a particularly blessed time to give in charity, as the reward is 700 times greater than any other time of the year. For that reason, Muslims will spend more in charity (sadaqa), and many will pay their zakat during Ramadhan, to receive the blessings (reward). In many Muslim countries, it is not uncommon to see people giving food to the poor and the homeless, and to even see large public areas for the poor to come and break their fast. It is said that if a person helps a fasting person to break their fast, then they receive a reward for that fast, without diminishing the reward that the fasting person got for their fast.
Sometimes referred to as "the night of decree or measures", Laylat al-Qadr is considered the most holy night of the year. Muslims believe that Laylat al-Qadr is the night in which the Qur'an was first revealed to the Prophet Muhammad. Also, it is believed to have occurred on an odd-numbered night during the last 10 days of Ramadan, either the night of the 21st, 23rd, 25th, 27th or 29th. Shiites also commemorate the attack on Imam `Ali ibn Abi Talib and his subsequent martyrdom every year on the 19th, 21st and 23rd of Ramadan.
The holiday of Eid ul-Fitr (Arabic: عيد الفطر) marks the end of the fasting period of Ramadan and the first day of the following month, after another new moon has been sighted. The Eid falls after 29 or 30 days of fasting, per the lunar sighting. Eid ul-Fitr means the back to the fitrah ; usually a special celebration is made. Food is donated to the poor (Zakat al-fitr); everyone puts on their best, usually new, clothes; and communal prayers are held in the early morning, followed by feasting and visiting relatives and friends. The prayer is two Raka'ah only, and it is sunnah muakkad  as opposed to the compulsory (Fard) five daily prayers. Muslims are expected to do this as an act of worship, and to thank God.
Eid ul-Fitr is celebrated for three days. Common greetings during this holiday are the Arabic greeting ‘Eid Mubārak ("Blessed Eid") or ‘Eid Sa‘eed ("Happy Eid"). In addition, many countries have their own greetings based on local language and traditions – in Turkey, for example, a typical saying might be Bayramınız kutlu olsun or "May your Bayram – Eid – be blessed." Muslims are also encouraged on this day to forgive and forget any differences or past animosities that may have occurred with others during the year.
Typically, Muslims wake up relatively early in the morning—always before sunrise— offer Salatul Fajr (the pre-sunrise prayer), and in keeping with the Sunnah (traditions and actions of the Prophet Muhammad), clean one's teeth with a Miswaak or toothbrush, take a shower (Ghusul) before Fajr prayers, put on new clothes (or the best available), and apply perfume.
It is haraam, or forbidden, to fast on the Day of Eid. That is why it is recommended to have a small breakfast (as a sign of not being on a fast on that day) of sweet dish, preferably the date fruit, before attending the special Eid prayer (salah). It is a Sunnah (Prophetic tradition) that the Sadaqat-ul-fitr, an obligatory charity, is paid to the poor and the needy before performing the ‘Eid prayer by all those adult Muslims who are required to pay Zakat. Muslims recite the following Takbir (incantation) in the low voice while going to the Eid prayer: Allahu Akbar, Allahu Akbar, Allahu Akbar. Laa ilaaha ilal-lahu wal-Allahu Akbar, Allahu Akbar wa-lilla hil hamd. Another Sunnah of Muhammad Muslims are recommended to use two separate routes to and from the prayer grounds.
Eid prayer is performed in congregation in open areas like fields, community centers, etc. or at mosques. No adhan (Call to Prayer) or iqama (call) is to be pronounced for this Eid prayer, and it consists of only two rakaʿāt (units of prayer) with an additional six Takbirs. The Eid prayer is followed by the khutbah (sermon) and then a supplication (dua) asking for God's forgiveness, mercy, peace and blessings for all living beings across the world. The khutbah also instructs Muslims as to the performance of rituals of Eid, such as the zakat. Listening to the khutbah (sermon) of Eid is a necessary requirement (wajib) i.e. while the khutbah is being delivered; it is haraam (prohibited) to talk, walk about or offer prayer while the sermon is being delivered. After the prayers, Muslims visit their relatives, friends and acquaintances or hold large communal celebrations in homes, community centers or rented halls.
Eid gifts(called eidi's in some cultures) are frequently given to children and immediate relatives; it is also common in some cultures for children to be given small sums of money by adult relatives or friends.