Path integrals are introduced and studied from different viewpoints, starting from the Feynman-Kac formula. Several realizations/interpretations of the functional measure are discussed. Specific topics include: (1) functional traces; (2) the path integral interpretation of finite-temperature partition functions; (3) time-ordered correlations, their generating functionals, and combinatorics; (4) symmetry, the Noether theorem, and Ward identities; (5) symmetry breaking; (6) diamagnetic inequalities; (7) semi-classical limits of path integrals; (8) \(\delta \) -functionals; (9) Gaussian path integrals; (10) spin, fermions, and Grassmanian path integrals; (11) supersymmetry vs. functional measures; (12) SUSY breaking from a path integral perspective. A large part of the chapter is devoted to exact techniques to compute path integrals: (a) four methods to find Green’s functions (propagators), (b) half a dozen ways to compute functional determinants; (c) three sections are dedicated to exact methods to compute certain non-Gaussian path integrals, including a novel, “recursion” method.