The word 'mosque' entered the English language from the French word mosquée, probably derived from Italian moschea (a variant of Italian moscheta), from either Middle Armenian մզկիթ (mzkit), Medieval Greek: μασγίδιον (masgídion), or Spanish mezquita, from Arabic: مسجد, romanized: masjid (meaning "site of prostration (in prayer)" and hence a place of worship), either from Nabataean masg dhā́ or from Arabic Arabic: سَجَدَ, romanized: sajada (meaning "to prostrate"), probably ultimately from Nabataean Arabic masg dhā́ or Aramaic s ghēdh.

Islam was established in Arabia during the lifetime of Muhammad in the 7th century CE. The first mosque in history could be either the sanctuary built around the Ka'bah in Mecca, known today as Al-Masjid al-Haram ('The Sacred Mosque'), or the Quba Mosque in Medina, the first structure built by Muhammad upon his emigration from Mecca in 622 CE, both located in the Hejaz region in present-day Saudi Arabia.

Other scholars reference Islamic tradition and passages of the Quran, according to which Islam as a religion precedes Muhammad, and includes previous prophets such as Abraham. In Islamic tradition, Abraham is credited with having built the Ka'bah in Mecca, and consequently its sanctuary, Al-Masjid al-Haram, which is seen by Muslims as the first mosque that existed. A hadith in Sahih al-Bukhari states that the sanctuary of the Ka'bah was the first mosque on Earth, with the second mosque being Al-Aqsa in Jerusalem, which is also associated with Abraham. Since as early as 638 CE, the Sacred Mosque of Mecca has been expanded on several occasions to accommodate the increasing number of Muslims who either live in the area or make the annual pilgrimage known as Hajj to the city.

Either way, after the Quba Mosque, Muhammad went on to establish another mosque in Medina, which is now known as Al-Masjid an-Nabawi ('The Prophet's Mosque'). Built on the site of his home, Muhammad participated in the construction of the mosque himself and helped pioneer the concept of the mosque as the focal point of the Islamic city. The Prophet's Mosque is considered by some scholars of Islamic architecture to be the first mosque. The mosque had a roof supported by columns made of palm tree trunks and it included a large courtyard, a motif common among mosques built since then. Rebuilt and expanded over time, it soon became a larger hypostyle structure. It probably served as a model for the construction of early mosques elsewhere. It introduced some of the features still common in today's mosques, including the niche at the front of the prayer space known as the mihrab (first added in the Umayyad period) and the tiered pulpit called the minbar.
• Aerial view of the Sacred Mosque (Al-Masjid Al-Ḥarām) of Mecca in Saudi Arabia, the largest mosque and holiest site in Islam, with the Kaaba in the center (2010 photo)
• The Prophet's Mosque (al-Masjid an-Nabawi) in Medina, Islam's second holiest site
• Masjid al-Qiblatayn (Mosque of the two Qiblahs) in Medina
• The Al-Aqsa Mosque in Jerusalem, Islam's third holiest site
The Umayyad Caliphate was particularly instrumental in spreading Islam and establishing mosques within the Levant, …

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There are two holidays (Eids) in the Islamic calendar: ʿĪd al-Fiṭr and ʿĪd al-Aḍḥā, during which there are special prayers held at mosques in the morning. These Eid prayers are supposed to be offered in large groups, and so, in the absence of an outdoor Eidgah, a large mosque will normally host them for their congregants as well as the congregants of smaller local mosques. Some mosques will even rent convention centers or other large public buildings to hold the large number of Muslims who attend. Mosques, especially those in countries where Muslims are the majority, will also host Eid prayers outside in courtyards, town squares or on the outskirts of town in an Eidgah.
Islam's holiest month, Ramaḍān, is observed through many events. As Muslims must fast during the day during Ramadan, mosques will host Ifṭār dinners after sunset and the fourth required prayer of the day, that is Maghrib. Food is provided, at least in part, by members of the community, thereby creating daily potluck dinners. Because of the community contribution necessary to serve iftar dinners, mosques with smaller congregations may not be able to host the iftar dinners daily. Some mosques will also hold Suḥūr meals before dawn to congregants attending the first required prayer of the day, Fajr. As with iftar dinners, congregants usually provide the food for suhoor, although able mosques may provide food instead. Mosques will often invite poorer members of the Muslim community to share in beginning and breaking the fasts, as providing charity during Ramadan is regarded in Islam as especially honorable.

Following the last obligatory daily prayer (ʿIshāʾ) special, optional Tarāwīḥ prayers are offered in larger mosques. During each night of prayers, which can last for up to two hours each night, usually one member of the community who has memorized the entire Quran (a Hafiz) will recite a segment of the book. Sometimes, several such people (not necessarily of the local community) take turns to do this. During the last ten days of Ramadan, larger mosques will host all-night programs to observe Laylat al-Qadr, the night Muslims believe that Muhammad first received Quranic revelations. On that night, between sunset and sunrise, mosques employ speakers to educate congregants in attendance about Islam. Mosques or the community usually provide meals periodically throughout the night

During the last ten days of Ramadan, larger mosques within the Muslim community will host Iʿtikāf, a practice in which at least one Muslim man from the community must participate. Muslims performing itikaf are required to stay within the mosque for ten consecutive days, often in worship or learning about Islam. As a result, the rest of the Muslim community is responsible for pro…

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