The word Mosque is the English equivalent of the word Masjid in Arabic. The word Masjid comes from the word sajada in Arabic, which means to prostrate. 

The primary function that Mosques play for Muslims is their role as a gathering place for communal prayers and worship. It is thus designed to be a means for communal salvation. 

In Islam, prayers are done both privately and publicly. The Mosque caters to both. People pray privately in Mosques for various reasons. For example, they may do their obligatory or recommended prayers. They may also perform iʿtikaf which is a practice of confining oneself to the Mosque for a number of days in order to perform religious rituals and activities. 

The Mosque is also a place for communal prayers. The five daily obligatory prayers are conducted in Mosques. The Friday prayers are also usually conducted in Mosques. In many Muslim countries, cities or areas within large cities have special Mosques dedicated for Friday prayers. These Friday Prayer Mosques are much larger in size so as to accommodate a larger number of people.