Nonfiction or non-fiction is content that purports in good faith to represent truth and accuracy regarding information, events, or people.^[1] Nonfiction content may be presented either objectively or subjectively, and may sometimes take the form of a story. Nonfiction is one of the fundamental divisions of narrative (specifically, prose)^[2] writing— in contrast to fiction, which offers information, events, or characters expected to be partly or largely imaginary, or else leaves open if and how the work refers to reality.^[1][3]

Nonfiction's specific factual assertions and descriptions may or may not be accurate, and can give either a true or a false account of the subject in question. However, authors of such accounts genuinely believe or claim them to be truthful at the time of their composition or, at least, pose them to a convinced audience as historically or empirically factual. Reporting the beliefs of others in a nonfiction format is not necessarily an endorsement of the veracity of those beliefs, but rather an exercise in representing the topic (for example, mythology). Most literary criticism is a form of nonfiction, providing information and analysis about works of fiction. Nonfiction need not necessarily be written text, since pictures and film can also purport to present a factual account of a subject.

The numerous literary and creative devices used within fiction are generally thought inappropriate for use in nonfiction. They are still present particularly in older works but they are often muted so as not to overshadow the information within the work. Simplicity, clarity and directness are some of the most important considerations when producing nonfiction. Audience is important in any artistic or descriptive endeavor, but it is perhaps most important in nonfiction. In fiction, the writer believes that readers will make an effort to follow and interpret an indirectly or abstractly presented progression of theme, whereas the production of nonfiction has more to do with the direct provision of information. Understanding of the potential readers' use for the work and their existing knowledge of a subject are both fundamental for effective nonfiction. Despite the truth of nonfiction, it is often necessary to persuade the reader to agree with the ideas and so a balanced, coherent and informed argument is vital. However, the boundaries between fiction and nonfiction are continually blurred and argued upon, especially in the field of biography;^[4] as Virginia Woolf said: "if we think of truth as something of granite-like solidity and of personality as something of rainbow-like intangibility and reflect that the aim of biography is to weld these two into one seamless whole, we shall admit that the problem is a stiff one and that we need not wonder if biographers, for the most part failed to solve it."^[5]

Semi-fiction is fiction implementing a great deal of nonfiction,^[6] e.g. a fictional description based on a true story.

Common literary examples of nonfiction include expository, argumentative, functional, and opinion pieces; essays on art or literature; biographies; memoirs; journalism; and historical, scientific, technical, or economic writings (including electronic ones).^[7]

Journals, photographs, textbooks, travel books, blueprints, and diagrams are also often considered nonfictional. Including information that the author knows to be untrue within any of these works is usually regarded as dishonest. Other works can legitimately be either fiction or nonfiction, such as journals of self-expression, letters, magazine articles, and other expressions of imagination. Though they are mostly either one or the other, it is possible for there to be a blend of both. Some fiction may include nonfictional elements. Some nonfiction may include elements of unverified supposition, deduction, or imagination for the purpose of smoothing out a narrative, but the inclusion of open falsehoods would discredit it as a work of nonfiction. The publishing and bookselling business sometimes uses the phrase "literary nonfiction" to distinguish works with a more literary or intellectual bent, as opposed to the greater collection of nonfiction subjects.^[8]