This is the first monograph devoted to investigation of the most complex physical processes - phase transitions, critical phenomena and super-molecular organization - of soft systems, including a wide class of solutions from associated to micellar ones. In the book their thermophysical parameters are determined. Special attention is paid to problems of emergence and stability of the microemulsion state. Modern theoretical understanding is accompanied by experimental results. New methods and models for the description of several soft systems are proposed. The book is intended for scientists, engineers, graduate and doctoral students interested in the problems of the physics of soft matter.