The development of scanning probe microscopy has made possible the investigation of sliding processes on contact areas as small as those formed by a single molecule and a crystal surface. Here, I will illustrate the progress in this field with representative examples of friction force imaging in different environments, ranging from ultra-high vacuum to liquid conditions on alkali halides, organic crystals and semiconducting surfaces. Sliding of graphene nanoribbons, single polymer chains and single-strand DNA at cryogenic temperatures will be also addressed to show potential applications in a rarely explored research field.