This is a presentation of the progress and current problems in the early universe, cosmic microwave background radiation, large scale structure formation, and the interplay between them. The emphasis is on the mutual impact of fundamental physics and cosmology, both at theoretical and experimental (observational) levels within a deep, well-focused and well-defined programme. The nature of the domain itself leads to different aspects, approaches and points of view on the same topic. Special care has been taken to provide the reader the basis of the different, sometimes competing lines of research.