The present book consists of contributions directed to the analysis of first- and second-order phase transitions from both experimental and theoretical points of view. They have been presented and discussed in the course of the research workshops «Nucleation Theory and Applications» organized at the Bogoliubov Laboratory of Theoretical Physics of the Joint Institute for Nuclear Research in Dubna, Russia, in the period from 2009 to 2011. The volume of the proceedings supplements results published in three former conference proceedings in the years 1999, 2002, 2005 and 2009 also in Dubna and two monographs with overview lectures published by WILEY-VCH in 1999 and 2005 as well as in a series of monographs by the participants. In the present proceedings, the spectrum of different topics includes experimental investigations of thermodynamic properties of matter (in thermodynamic equilibrium and non-equilibrium states including glasses), nucleation-growth phenomena and their theoretical interpretation, the theoreti