Introduction to Berkovich analytic spaces.- Etale cohomology of schemes and analytic spaces.- Countability properties of Berkovich spaces.- Cohomological finiteness of proper morphisms in algebraic geometry: a purely transcendental proof, without projective tools.- Bruhat-Tits buildings and analytic geometry.- Dynamics on Berkovich spaces in low dimensions.- Compactifications of spaces of representations (after Culler, Morgan and Shalen).