The life of a protein, from birth till death, is complex and challenging. At times, because of stresses or bad luck, it might take the wrong conformation and start aggregating. This process is intrinsic to the physics of proteins, and life has had to cope with it since its early days. The solution devised by evolution comes in the form of chaperone protein, a broad class of machines, present in all organisms on Earth, that repair conformationally damaged proteins, making them functional again, at an energy cost. In this talk I will provide a view of our present understanding of the molecular mechanism of function of Hsp70, possibly the most central of all chaperones, and of its consequences on proteins.