Ever since 1911‎,‎ the Solvay Conferences have shaped modern physics‎.‎ The 25th edition held in October 2011 in Brussels and chaired by David Gross continued this tradition and celebrated the first centennial of this illustrious series of conferences‎.‎ The development and applications of quantum mechanics have always been the main threads in the history of the Solvay Conferences‎,‎ hence the 25th Solvay conference gathered many of the leading figures working on a wide variety of profound problems in physics where quantum mechanical effects play a central role‎.‎ The conference addressed some of the most pressing open questions in the field of physics‎.‎The proceedings contain the ‎"‎rapporteur talks‎"‎ which give a broad overview with unique insights by distinguished and renowned scientists‎.‎ These lectures cover the seven sessions‎:‎ ‎"‎History and Reflections‎"‎‎,‎ ‎"‎Foundations of Quantum Mechanics and Quantum Computation‎"‎‎,‎ ‎"‎Control of Quantum Systems‎"‎‎,‎ ‎"‎Quantum Condensed Matter‎"‎‎,‎ ‎"‎Particles and Fields‎"‎‎,‎ ‎"‎Quantum Gravity and St‎.‎‎.‎‎.‎