Usool ul-Fiqh

Usoolul-Fiqh: it is the science concerning the comprehensive evidences of fiqh. Since fiqh consist of either [i] masaa‘il (issues) concerning which the ruling by one of the five rulings is sought, or [ii] it is the dalaa‘il (evidences) employed in extracting and determining these masaa‘il (issues). So fiqh is actualy knowledge of the masaa‘il (issues) and the dalaa‘il (evidences).