Low-temperature physics has undergone rapid development over the past two decades, both theoretically and experimentally. The main tool of theoretical low-temperature physics is the many- body theory. It is extremely interesting to elucidate the relevant problems and progress achieved in this very important field of research in light of the current keen interest in phase transitions and formal analogies between statistical mechanics and field theory. In the field of low-temperature physics, the following topics are included: – superfluidity and l point, phonon dispersion in superfluid helium, first and second sounds (both theoretically and experimentally) – superconductivity, hard and soft superconductors, BCS theory, experimental techniques – cooling techniques, low temperature calibration – sub-monolayer helium films. (This is a recent but exciting field, where we see the most interesting examples of Onsager transitions).