What is handwriting analysis called?

Graphology, inference of character from a persons handwriting. The theory underlying graphology is that handwriting is an expression of personality; hence, a systematic analysis of the way words and letters are formed can reveal traits of personality.

Is faking a signature illegal?

Forgery involves a false document, signature, or other imitation of an object of value used with the intent to deceive another. Those who commit forgery are often charged with the crime of fraud. Most states require that forgery be done with the intent to commit fraud or larceny.

What happens if I use a fake signature?

When an individual creates a false document or alters a legitimate contract with the intent to be fraudulent, then this is considered forgery and is usually considered a crime. By changing the amount, that individual has performed an act of forgery and is subject to criminal punishment, such as fines or imprisonment.