Allah has commanded us to worship and obey Him with sincerity, reverence, love, and gratitude. He says in the Qur’an: “And they are ordered only to serve Allah, keeping religion pure for Him, to remain upright, and to establish worship and to pay the poor due. That is true religion” (98:5). This worship is not possible without knowledge. This short work outlines the absolute essentials of this knowledge. It is based on the methodology of traditional Sunni Islam, according to the Shafi’i school of Islamic law, and its purpose is to make one’s worship valid, sound, and proper in a short amount of time.