The aim of this paper is an ontological clarification of the concept of artefact. The following questions are addressed: 1. Do artefacts constitute an ontological category of objects in its own right, and if so, how could this category be characterized? 2. How do artefacts come into existence? 3. What kind of artefacts are there, and in which relations do they stand to each other? It is argued that artefacts are characterized essentially through their genesis and that they owe their existence to mental acts of a particular kind, which I call “acts of creation”. It is maintained that there are not only concrete, material artefacts, but also abstract artefacts, that is, artefacts that cannot be perceived through the senses and are not located in space. Furthermore, it shall be claimed that in a sense those abstract artefacts are even primary to the concrete, material artefacts.