It is not always known who painted a picture. An attribution is an assessment of who was responsible for creating a particular work.
Attributions are made with different degrees of certainty, depending on factors such as style and documentary and scientific evidence:
- 'by Raphael' shows reasonable certainty about the attribution
- 'attributed to Raphael' intimates a degree of doubt about the authorship of the picture
- 'by the Studio of Raphael' means painted by a pupil of the named artist, probably under his direction
- 'a Follower of Raphael' is someone who admired the artist's style, but was not necessarily a pupil of his
- 'an Imitator of Raphael' is one who slavishly admired the artist, but may have worked at a much later date