A dissertation or thesis is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings. In some countries/universities, the word "thesis" or a cognate is used as part of a bachelor's or master's course, while "dissertation" is normally applied to a doctorate, while in others, the reverse is true.

The term dissertation can at times be used to describe a treatise without relation to obtaining an academic degree. The term thesis is also used to refer to the central claim of an essay or similar work.

The word "thesis" comes from the Greek θέσις, meaning "position", and refers to an intellectual proposition. "Dissertation" comes from the Latin dissertātiō, meaning "discourse".

A typical thesis (or dissertation) has a title page, an Abstract, a table of contents, a body, comprising the various chapters (introduction, literature review, findings, etc.), and a bibliography or (more usually) a references section. They vary in their structure in line with the many different areas of study (arts, humanities, social sciences, technology, sciences, etc.) and the great differences between them.