This volume is a collection of the Nobel lectures delivered by the prizewinners, together with their biographies and the presentation speeches for the period 2001 - 2005. Each Nobel lecture is based on the work for which the laureate was awarded the prize. This volume of inspiring lectures by outstanding physicists should be on the bookshelf of every keen student, teacher and professor of physics as well as of those in related fields.Below is a list of the prizewinners during the period 2001 - 2005 with a description of the works which won them their prizes.(2001) Eric A Cornell, Wolfgang Ketterle & Carl E Wieman -- for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates; (2002) Raymond Davis Jr, Masatoshi Koshiba -- for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos & Riccardo Giacconi -- for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources; (2003) Alexei A Abrikosov, Vitaly L Ginzburg & Anthony J Leggett -- for pioneering contributions to the theory of superconductors and superfluids; (2004) David J Gross, H David Politzer & Frank Wilczek -- for the discovery of asymptotic freedom in the theory of the strong interaction; (2005) Roy J Glauber, John L Hall & Theodor W Hänsch -- for their contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique.