TITLE: On the use of Lyapunov exponents to detect global properties of the dynamics AUTHOR: Carles Sim\'o Departament de Matem\`atica Aplicada i An\`alisi, Universitat de Barcelona, Gran Via, 585, 08071 Barcelona (Spain) ABSTRACT: Different methods have been proposed for the numerical computation of Lyapunov exponents. After a quick review we shall describe a new powerful method which is specially suitable to detect domains of ordered motions. Then several examples will be presented, applied to conservative and non-conservative systems, discrete and continuous. They show how one can obtain relevant information on the global dynamics in a fast way. Finally, an application to compute the metric entropy of a family of diffeomorphisms will be done. In that case to have an accurate value of the entropy is important to support different conjectures.