  In the context of a physical theory, two devices, A and B, described by the
theory are called incompatible if the theory does not allow the existence of a
third device C that would have both A and B as its components. Incompatibility
is a fascinating aspect of physical theories, especially in the case of quantum
theory. The concept of incompatibility gives a common ground for several famous
impossibility statements within quantum theory, such as ``no-cloning'' and ``no
information without disturbance''; these can be all seen as statements about
incompatibility of certain devices. The purpose of this paper is to give a
concise overview of some of the central aspects of incompatibility.
