There are four types of Qias (Analogical Reasoning) in Islamic jurisprudence: (1) Qiyas al-'Illah (reasoning by effective cause), (2) Qiyas al-Dalalah (reasoning by indication), (3) Qiyas al-Shabah (reasoning by resemblance), and (4) Qiyas al-Tard (reasoning by co-existence). Qias is the fourth source of Islamic law after Quran, Sunnah, and Ijma.