In general, an artist is one who produces or creates all kinds of art, such as sculptures, paintings, or music. When metadata is involved, it is what you see. Artist information is typically included in audio recordings. They provide information on the Artist or group that performed, however, they are not always who composed the song or recorded the piece of music.
The Artist may also be seen in some images. In particular, it is found in photos that are either in raw format (CR2 NEF, ARW, or similar.) or are already edited and stored for sharing and publication (JPG, PNG, etc.). In this case, the Artist refers to the photographer who captured the image.