This book presents a collection of selected reviews from PLMMP 2018 that address modern problems in the fields of liquids, solutions and confined systems, critical phenomena, as well as colloidal and biological systems. The papers focus on state-of-the-art developments in the contemporary physics of liquid matter, and are divided into four parts: (i) water and water systems, (ii) physical–chemical properties of liquid systems, (iii) aggregation in liquid systems, and (iv) biological aspects of liquid systems, irradiation influences on liquid systems. Taken together, they cover the latest developments in the broader field of liquid states, including interdisciplinary problems.