Unsolved problems in fundamental physics

Recent years have added very much to our knowledge of the structure of the Universe and elementary interactions which, combined with the critical rethinking of long-known results and ideas, gives considerable topical relevance to the questions listed in this paper. Compiling this list, the author had no notion of any targeting and the typical 'WHAT FOR' and 'WHY' questions were considered as mere abbreviations for 'Does a (possibly yet unknown) law of Nature exist with which the property or phenomenon under study can be explained?' The list of problems reflects the scientific interests of the author and so does not claim to be comprehensive. (methodological notes)