A mosque is a place of worship for followers of Islam. Muslims often refer to the mosque by its Arabic name, masjid, Arabic: مسجد‎ — Arabic pronunciation: ['mæsdʒɪd] (pl. masajid, Arabic: مساجد‎ — [mæ'sæːdʒɪd]).

The word 'mosque' in English refers to all types of buildings dedicated for Islamic worship, although there is a distinction in Arabic between the smaller, privately owned mosque and the larger, 'collective' mosque (Arabic: مسجد جامع‎, masjid jami‘), which has more community and social amenities.
The mosque serves as a place where Muslims can come together for salat (prayer) (Arabic: صلاة‎, ṣalat) as well as a center for information, education, and dispute settlement. The Imam leads the prayer.
They have developed significantly from the open-air spaces that were the Quba Mosque and Al-Masjid al-Nabawi in the 7th century. Many mosques have elaborate domes, minarets, and prayer halls. Mosques originated on the Arabian Peninsula, but are now found in all inhabited continents.

Source: tebyan