Abstract
We introduce and discuss basic topics in the theory of kaons and charmed particles. In the first part, theoretical methods in weak decays such as operator product expansion, renormalization group and the construction of effective Hamiltonians are presented, along with an elementary account of chiral perturbation theory. The second part describes the phenomenology of the neutral kaon system, CP violation, \varepsilon and \varepsilon'/\varepsilon, rare kaon decays (K\to\pi\nu\bar\nu, K_L\to\pi^0 e^+e^-, K_L\to\mu^+\mu^-), and some examples of flavour physics in the charm sector.