Performing prayer (Salat) is the most compulsory act in Islam, after the declaration of faith (shahadah).
The Salat must be performed in the Arabic language to the best of each worshipper's ability (although the du'a afterwards need not be in Arabic), and are to be recited by heart, although beginners may use written aids. The person performing salah is referred to as a musalleeh.
All Salat should be conducted within their waqt (prescribed time) and with the appropriate number of raka'ah. While they may be prayed at any point within the waqt, it is considered best to pray them exactly at the beginning of their periods, when the call to prayer (adhan) announces the time of prayer. When too far from a mosque to hear a call to prayer, the time may be inferred from the position of the sun in the sky.