Introduction -- Martingales and simple ruin calculations -- Further general tools and results -- The compound Poisson model -- The probability of ruin within finite time -- Renewal arrivals -- Risk theory in a Markovian environment -- Level-dependent risk processes -- Matrix-analytic methods -- Ruin probabilities in the presence of heavy tails -- Ruin probabilities for Lévy processes -- Gerber-Shiu functions -- Further models with dependency -- Stochastic control -- Simulation methodology -- Miscellaneous topics.