Multiplier ideals in algebraic geometry

In this expository introductory text we discuss the multiplier ideals in algebraic geometry. We state Kawamata-Viehweg's and Nadel's vanishing theorems, give a proof (following Ein and Lazarsfeld) of Koll\'ar's bound on the maximal multiplicity of the theta divisor, and explain the asymptotic constructions and the ideas of Siu's proof of the deformation invariance of plurigenera. We also indicate the analytic interpretation of the theory.