Introduction -- Separation of the Elastic and Inertial Properties in Three-dimensional Systems -- Normal Contact Problems with Axially-symmetric Bodies without Adhesion -- Normal Contact with Adhesion -- Tangential Contact -- Rolling Contact -- Contact with Elastomers -- Heat Transfer and Heat Generation -- Adhesion with Elastomers -- Normal Contact of Rough Surfaces -- Frictional Force -- Frictional Damping -- Coupling to Macroscopic Dynamics -- Acoustic Emission in Rolling Contacts -- Coupling to the Microscale -- And Now What -- Appendix.