Fuzzy logic and fuzzy set theory provide the conceptual basis for modeling the spatial continuity of many geographic entities lacking clear boundaries and a practical framework for managing uncertainty and imprecision in GIS models. The cognitive basis of fuzzy models is rooted in prototype category theory, which posits that humans perceive and interpret the world through categorical structures. Categories, formed through human interaction with the environment, exhibit non-uniform membership, with certain members serving as better exemplars, known as 'prototype effects'. When classifying geographic features that display prototype effects, fuzzy logic provides an effective method for their representation and for modeling the associated uncertainty in the classification process. One of the primary applications of fuzzy models in GIS is fuzzy inference for decision-making. A fuzzy inference system consists of a knowledge base comprising fuzzy membership functions and a set of fuzzy rules. Common applications include predictive soil mapping, risk modeling, suitability analysis, and site selection using multi-criteria decision analysis. Recent advancements in fuzzy GIS models leverage hybrid models that integrate fuzzy multi-criteria decision analysis with advanced analytics such as AI/machine learning.