In virtually every structural, mechanical and biological system, it is by way of contact that bodies interact, coming in to touch and interchanging energy. Despite being something mundane, the physics of contact interaction is particularly complex and of multi-scale and multi-physics character. A great example is a fundamental observation that all engineering surfaces are rough, at a sufficiently small scale of inspection. It is intimately connected with the contact interaction properties, determining the morphology and physics at the interface. Therefore, contact problems are inherently non-linear, making them difficult to solve without resorting to approximate techniques. Taking into account that experimental research on this subject can be very expensive/time-consuming, or sometimes even non-feasible, the field of computational contact mechanics is an ever-growing field of research, demanding powerful numerical techniques that are able to accurately predict contact phenomena.