Rough contact mechanics is an issue that draws increasingly wide research efforts, involving analytic, numerical and experimental investigations. Lots of macroscopic phenomena, like friction, wear, structural damping, are strongly influenced by the roughness of the contacting surfaces. Indeed, strong interest in these topics has been the consequence of the increasing efforts made to face up new technological challenges, such as the manufacturing of novel bio-inspired adhesives, the optimized design of tires and seals, the extreme downsizing of mechanical and electrical devices down to the nano-scales. This book reviews the main analytic, numerical and experimental methods proposed to study these subjects. Furthermore, it contains a detailed description of numerical approaches developed by the author and successfully employed to study the rough contact mechanics. Special attention is paid to contact area, contact stiffness, and viscoelastic dissipation. Finally, some innovative experimental methodologies are introduced to grasp the main contact features and to validate the numerical simulations.