A more thorough explanation:

Definition: Autograph is a word used to describe a person's own writing or signature. It is also known as a holograph. Autograph is different from allograph, which is someone else's writing or signature.

• When I met my favorite celebrity, I asked for their autograph on a piece of paper.
• The book was valuable because it had the author's autograph on the first page.
• My grandmother showed me a letter from her great-grandfather that had his autograph at the bottom.

These examples illustrate how autograph refers to a person's own writing or signature. In the first example, the celebrity signed their name on a piece of paper. In the second example, the author signed their name in the book. In the third example, the great-grandfather wrote the letter and signed it with his own handwriting.