  This review, of the understanding of quantum mechanics, is broad in scope,
and aims to reflect enough of the literature to be representative of the
current state of the subject. To enhance clarity, the main findings are
presented in the form of a coherent synthesis of the reviewed sources. The
review highlights core characteristics of quantum mechanics. One is statistical
balance in the collective response of an ensemble of identically prepared
systems, to differing measurement types. Another is that states are
mathematical terms prescribing probability aspects of future events, relating
to an ensemble of systems, in various situations. These characteristics then
yield helpful insights on entanglement, measurement, and widely-discussed
experiments and analyses. The review concludes by considering how these
insights are supported, illustrated and developed by some specific approaches
to understanding quantum mechanics. The review uses non-mathematical language
precisely (terms defined) and rigorously (consistent meanings), and uses only
such language. A theory more descriptive of independent reality than is quantum
mechanics may yet be possible. One step in the pursuit of such a theory is to
reach greater consensus on how to understand quantum mechanics. This review
aims to contribute to achieving that greater consensus, and so to that pursuit.
