Ilm al-Hal is a handbook of every Muslim individual and family. It consists of issues common to all believers without exception and information about their responsibilities that begin as soon as they reach puberty. These can be summarized as the lawful and the prohibited that are encountered in Islamic creed, acts of worship and daily life. We can call all these “priority information”. Because a person whose standards of faith are wrong and does not know how to serve Allah cannot be expected to observe Islamic standards in other areas of life. The "Basic Islamic Principles (ʿIlmi Ḥāl) According to Four Sunni Schools" aims to provide the criteria by highlighting their basis in the Qur'an and Sunnah. Its purpose is to confront the Muslims with the Owner of Ruling, thus reminding the divine dimension of their responsibility. The process of acquiring Islamic knowledge, which starts with learning the principles of creed, acts of worship and daily life found in this book and then and living in accordance with that knowledge, will lead the person to adopt Islam as a whole life system. Because Islam, in fact, encompasses the whole life.