Modification; changing a thing without obliterating it.
An alteration is a variation made in the language or terms of a legal document that affects the rights and obligations of the parties to it. When this occurs, the alteration is material and the party who did not consent to the change can be released from his or her duties under the document by a court.
When an essential part of a writing has been cut, torn, burned, or erased, the alteration is also known as a mutilation.
The alteration of a document by someone other than a party to it is called a spoliation.