This is the fourth volume in the series "Advances in Contact Angle, Wettability and Adhesion" initiated to consolidate information and provide commentary on certain recent research aspects dealing with this important topic. Its predecessor Volumes 1, 2 and 3 were published in 2013, 2015 and 2018 respectively. This new book comprising 14 research and review articles is divided into four parts: Part 1: Contact Angle and Wettability Aspects; Part 2: Surface Free Energy and Surface Tension Determination; Part 3: Applied Aspects. The topics covered include: Contact Angle Determination of Talc Powders from Heat of Immersion Surface Wetting at Macro and Nanoscale Wettability of Wood Surfaces with Waterborne Acrylic Lacquer Stains Modulated by DBD Plasma Treatment in Air at Atmospheric Pressure Wettability of Ultrafiltration Membranes      Determination of the Surface Free Energy of Solid Surfaces: Can the Best Model be Found Surface Free Energy Characterization of Talc Powders Determination of the Surface Free Energy of Skin and the Factors Affecting it by the Contact Angle Method Determination of Surface Tension Components of Aqueous Solutions using Fomblin HC/25 R Perfluoropolyether Liquid Film as a Solid Substrate Enhancing the Wettability of Polybenzimidazole (PBI) to Improve Fuel Cell Performance Evaluation of Sebum Resistance for Long-Wear Face Make-Up Products Using Contact Angle Measurements Contact Angle Hysteresis of Pressure-Sensitive Adhesives due to Adhesion Tension Relaxation The Potential of Surface Nano-Engineering and Superhydrophobic Surfaces in Drag Reduction Laser Surface Engineering of Polymeric Materials for Enhanced Mesenchymal Stem Cell Adhesion and Growth Sisal-Green Resin Interfaces in Green Composites.