This book addresses physicists working in general
relativity, astrophysics and cosmology. The contributions
are based on reports given at a summer school the goal of
which was to review modern research for students. The school
was centered on the study of gravitational fields
corresponding to rotating objects of astrophysical interest,
under different viewpoints: theoretical, numerical and
observational. Special emphasis is put on the analysis of
interior and exterior fields of stationary axisymmetric
systems. Lectures and contributions, collected here in Part
I, ranged from basic information useful to newcomers to
technical points pertaining to current research in this
area. Part II contains lectures and contributions on other
aspects of gravitation theory.