It provides the reader with the essential background about latent variable models, and in particular the latent class model. It explains the Markov chain model that, together with latent class model, represents a useful paradigm for latent Markov models. The assumptions of the basic version of the latent Markov model are illustrated in the presence of univariate or multivariate responses without covariates. Maximum likelihood estimation through the Expectation-Maximization algorithm is introduced. Then, it shows some constrained versions of the basic latent Markov model based on parsimonious and interpretable parametrizations. The inclusion of the individual covariates is introduced with the random-effects and the multilevel extensions of the model.