An
identity document (also called a
piece of identification or
ID, or colloquially as
papers) is any
document which may be used to identify a person or verify aspects of a person's
personal identity. If issued in a small, standard credit card size form, it is usually called an
identity card (
IC or
ID card). Some countries issue formal identity documents, while others may require identity verification using informal documents. When the identity document incorporates a person's photograph, it may be called
photo ID.