The graphologist applies his skills mainly to handwritten documents.
Among these, some occur more frequently than others—an each has its own peculiarity.

• Cheques, often bearing handwriting from more than one person. The analysis of the numbers is often fundamental. It is often to be verified that numbers or letters were not added at a second time.
• Private contracts, often handwritten for reasons of convenience and time—here too it is important to single out parts that might have been added after the "official" writing.
• Anonymous letters, which are much more widespread than one would imagine.
• Wills, in which the main problem are the often compromised health of the writer (Alzheimer e Parkinson diseases, for instance) and the frequent lack of temporally close comparative documents.
• Paintings and works of art, for which the expert does not investigate the artistic technique, but simply examines the signature that might have been written (presumably) by the artist.