The aim of this paper is to give a systematic account of the so-called "measurement problem" in the frame of the standard interpretation of quantum mechanics. It is argued that there is not one but five distinct formulations of this problem. Each of them depends on what is assumed to be a "satisfactory" description of the measurement process in the frame of the standard interpretation. Moreover, the paper points out that each of these formulations refers not to a unique problem, but to a set of sub-problems.