Book excerpt: This book summarizes the recent development of nuclear science as an important part of mesoscopic physics, the intermediate world between the macroscopic and microscopic. This fast developing area with many practical applications includes complex atoms, molecules (including biological), nuclei, small-scale solid state systems, and future quantum computers. The complexity of the problem appears due to the richness of problems, from the necessity to study individual quantum levels, to the fundamental features of statistics and thermodynamics.