The handwriting expert looks for idiosyncrasies in a person's handwriting to distinguish one individual's writing from another. Everyone has three styles of handwriting: natural, when the brain is concentrating on getting information on paper; formal, when one is writing an important letter; and unnatural, when one intentionally modifies the writing in order to improve, disguise, or imitate. Many factors affect handwriting: moods, mental and physical ailments, the taking of alcohol and drugs, the materials used, the conditions under which the handwriting is produced, and how often the person writes. Nobody can produce two identical signatures. In order to identify handwriting, the forensic expert must know the effect these factors have on writing and must be aware of such variables as the amount of pressure used in writing, the size of the writing, and the speed at which the characters are produced. Equipment used in demonstrating handwriting includes visual aids and a comparison microscope. Other equipment used in handwriting analysis includes infra-red scanners to separate various shades of ink and ultra-violet light to examine any modification to paper by erasure or chemicals. Case histories are presented to show the challenges a forensic handwriting expert faces. For the foreseeable future, handwriting experts will be needed, because computers cannot be feasibly programmed to detect fraudulent handwriting.