A mosque is symbolically very important to Muslims, being a humble way for humans to recreate pure divine presence on earth. But mosques are not built according to divine patterns (as is alleged by many other religions) — they are simply divinely guided. The main religious texts provide no clear rules as to what a mosque should look like.
Mandatory elements for a mosque include that it should point the direction to Mecca (this direction is called qibla). This indication in most mosques is a mihrab, a niche in the wall. The area in front of the mihrab must be roofed. In the wall of the mihrab there can be no doors. As for the other walls, there can be as many doors as the builders want.
There are 2 types of mosques: the main mosque is called jama'a, and is the one where the Friday prayer is recited. The jama'as are often richly adorned. In English, the term jama'a is rarely used, "Friday Mosque" or "Great Mosque" being the common term.
The other type of mosque is called masjid, and is the local and smaller mosque. While these can be richly adorned, they can seldom be compared to the jama'as.
Masjid is a word meaning 'place for prostration' and they were used by the early Muslims for houses of worship, even at times for other religions. Today the Arabic 'masjid', and the English 'mosque', are used exclusively for the religious houses of Islam. With the significant increase in jamacas (main mosques) after the 9th century, the term 'masjid' came more and more to be used for small and insignificant mosques.
Mosques form centres in cities, or in neighbourhoods of cities. This function does not always have to be structured, but it can be connected to mentality, so that the establishment of a new mosque often facilitates the emergence of a city centre. This characteristic was typical in older days, but is becoming more and more unusual.
Very few mosques lie in open areas, and very few mosques do not have shops and commercial activities in the streets around it. People's houses are often lying in a second "circle" around the mosque and the shops. Other social functions that have often been connected to mosques, include schools, law courts, hospitals and lodging for travellers. This pattern is based upon the Madina mosque, but is of less importance today, since city planning more and more uses Western models.