A diploma is a document awarded by an educational institution (such as a college or university) testifying the recipient has graduated by successfully completing their courses of studies. Historically, it has also referred to a charter or official document of diplomacy.

The diploma (as a document certifying a qualification) may also be called a testamur, Latin for "we testify" or "certify" (testari), so called from the word with which the certificate begins; this is commonly used in Australia to refer to the document certifying the award of a degree. Alternatively, this document can simply be referred to as a degree certificate or graduation certificate, or as a parchment. The certificate that a Nobel laureate receives is also called a diploma.

The term diploma is also used in some historical contexts, to refer to documents signed by a King affirming a grant or tenure of specified land and its conditions (see Anglo-Saxon Charters and Diplomatics).