These slides constitute a 12h introductory course on global optimization. The course starts with basic concepts specific to global optimization and different from those underlying local optimization algorithms. A selection of 6 algorithms is then presented: random search, randomly restarted local searches, simulated annealing, CMA-ES and Bayesian Optimization. This selection is meant to cover the main mechanisms behind global searches. Pre-requisites are: linear algebra, basic probabilities and local optimization (gradient methods, necessary optimality conditions).