The takbīr is the name for the Arabic phrase Allāhu ʾakbar.
A Muslim raises both of his hands to recite the takbīr in prayer.
Calligraphic Takbir in minaret of Sancaklar Mosque.
Allāhu akbar in a memorial, Desouk, Egypt
Allāhu akbar in Arabic calligraphy seen on Imam Ali Mosque architecture (center of the Iwan), 1994
Salah, is the principal form of worship in Islam. Facing Mecca, it consists of units called rak'a, during which the Quran is recited, and prayers from the Sunnah are typically said. The number of rak'a varies from prayer to prayer. Minor details of performing salah may differ according to the madhhab of the person performing it.
The prayer room in Khonakhan Mosque, Uzbekistan
Various prescribed movements in salah, which collectively constitute a rak'ah. From left to right: rukū', qiyām/i'tidal, sujūd, takbīr and qu'ūd/julūs.
Women performing the Friday prayer at a mosque, Ohio, US
A Sunni Muslim (left) and Shia Muslim (right) performing the Friday prayer in Tehran. Some Sunnis perform salah with the hands clasped ("qabd"), while Shia offer salah with their hands at their sides ("sadl").