This document discusses various methods for defuzzification, which is the process of converting a fuzzy quantity into a crisp quantity. It describes seven common defuzzification methods: 1) max membership principle, 2) centroid method, 3) weighted average method, 4) mean max membership, 5) center of sums, 6) centre of largest area, and 7) first of maxima, last of maxima. For each method, it provides details on the calculation approach and formulas used to determine the defuzzified crisp value. The centroid method is noted as the most commonly used defuzzification technique.