Friday prayer in the context of "Naqsh-e Jahan Square"

Salah (Arabic: ٱلصَّلَاةُ, romanized: aṣ-Ṣalāh, also spelled Salat), also known as Namaz (Persian: نماز, romanized: namāz), is the practice of formal worship in Islam, consisting of a series of ritual prayers performed at prescribed times daily. These prayers, which consist of units known as rak'ah, include a specific set of physical postures, recitation from the Quran, and prayers from the Sunnah, and are performed while facing the direction towards the Kaaba in Mecca (qibla). The number of rak'ah varies depending on the specific prayer. Variations in practice are observed among adherents of different madhahib (schools of Islamic jurisprudence). The term salah may denote worship in general or specifically refer to the obligatory prayers performed by Muslims five times daily, or, in some traditions, three times daily.

The obligatory prayers play an integral role in the Islamic faith, and are regarded as the second and most important, after shahadah, of the Five Pillars of Islam for Sunnis, and one of the Ancillaries of the Faith for Shiites. In addition, supererogatory salah, such as Sunnah prayer and Nafl prayer, may be performed at any time, subject to certain restrictions. Wudu, an act of ritual purification, is required prior to performing salah. Prayers may be conducted individually or in congregation, with certain prayers, such as the Friday and Eid prayers, requiring a collective setting and a khutbah (sermon). Some concessions are made for Muslims who are physically unable to perform the salah in its original form, or are travelling.

A mosque (/mɒsk/ MOSK), also called a masjid (/ˈmæsdʒɪd, ˈmʌs-/ MASS-jid, MUSS-), is a place of worship for Muslims. The term usually refers to a covered building, but can be any place where Islamic prayers are performed; such as an outdoor courtyard.

Originally, mosques were simple places of prayer for the early Muslims, and may have been open spaces rather than elaborate buildings. In the first stage of Islamic architecture (650–750 CE), early mosques comprised open and closed covered spaces enclosed by walls, often with minarets, from which the Islamic call to prayer was issued on a daily basis. It is typical of mosque buildings to have a special ornamental niche (a mihrab) set into the wall in the direction of the city of Mecca (the qibla), which Muslims must face during prayer, as well as a facility for ritual cleansing (wudu). The pulpit (minbar), from which public sermons (khutbah) are delivered on the event of Friday prayer, was, in earlier times, characteristic of the central city mosque, but has since become common in smaller mosques. To varying degrees, mosque buildings are designed so that there are segregated spaces for men and women. This basic pattern of organization has assumed different forms depending on the region, period, and Islamic denomination.

A congregational mosque or Friday mosque (Arabic: مَسْجِد جَامِع, romanized: masjid jāmi‘, or simply جَامِع, jāmi‘; Turkish: Cami), or sometimes great mosque or grand mosque (جامع كبير, jāmi‘ kabir; Ulu Cami), is a mosque for hosting the Friday noon prayers known as jumu'ah. It can also host the Eid prayers in situations when there is no musalla or eidgah available nearby to host the prayers. In early Islamic history, the number of congregational mosques in one city was strictly limited. As cities and populations grew over time, it became more common for many mosques to host Friday prayers in the same area. In early centuries, the congregational mosque was also a center of social and public life, hosting various other activities in addition to prayers, such as judicial and educational functions.

Ghusl (Arabic: غسل ġusl, IPA: [ˈɣʊsl]) is an Arabic term that means the full-body ritual purification which is mandatory before the performance of various Islamic activities and prayers. For any Muslim, it is performed after sexual intercourse (i.e. it is fardh), before Friday prayer and prayers for Islamic holidays, before entering the ihram in preparation for Hajj, after having lost consciousness, and after formally converting to Islam. Sunni Muslims also perform the ablution before Salat al-Tawba "Prayer of Repentance".

Ghusl is often translated as "full ablution", as opposed to the "partial ablution" or wudu وضوء that Muslims perform after lesser impurities such as urination, defecation, flatulence, deep sleep, and light bleeding (depending on the madhhab).

This article lists mosques from around the world by available capacity, that belong to any Islamic school or branch, that can accommodate at least 15,000 worshippers in all available places of prayer such as prayer halls (musala), courtyards (ṣaḥn) and porticoes (riwāq). All the mosques in this list are congregational mosques – a type of mosque that hosts the Friday prayer (ṣalāt al-jumuʿa) in congregation (jamāʿa).