Paul Turan, one of the greatest Hungarian mathematicians, was born 100 years ago, on August 18, 1910. To celebrate this occasion the Hungarian Academy of Sciences, the Alfred Renyi Institute of Mathematics, the Janos Bolyai Mathematical Society and the Mathematical Institute of Eoetvoes Lorand University organized an international conference devoted to Paul Turan's main areas of interest: number theory, selected branches of analysis, and selected branches of combinatorics. The conference was held in Budapest, August 22-26, 2011. Some of the invited lectures reviewed different aspects of Paul Turan's work and influence. Most of the lectures allowed participants to report about their own work in the above mentioned areas of mathematics.