As a literary genre, a memoir (from the French: mémoire from the Latin memoria, meaning "memory"), or a reminiscence, forms a subclass of autobiography – although the terms 'memoir' and 'autobiography' are today almost interchangeable. The author of a memoir may be referred to as a memoirist.

Memoirs nature can be seen as

Memoirs may appear less structured and less encompassing than formal autobiographical works as they are usually about part of a life rather than the chronological telling of a life from childhood to adulthood/old age. Traditionally, memoirs usually dealt with public matters, rather than personal, and many older memoirs contain little or no information about the writer, and are almost entirely concerned with other people. Also, many memoirs deal with one certain moment that is stretched out to show emphasis. They tended to be written by politicians or people in court society, later joined by military leaders and businessmen, and often dealt exclusively with the writer's careers rather than their private life. Modern expectations have changed this, even for heads of government. Like most autobiographies, memoirs are generally written from the first person point of view.

Gore Vidal, in his own memoir Palimpsest, gave a personal definition: "a memoir is how one remembers one's own life, while an autobiography is history, requiring research, dates, facts double-checked." It is more about what can be gleaned from a section of one's life than about the outcome of the life as a whole.

Contemporary practices of writing memoirs for recreational, family or therapeutic purposes are sometimes referred to as legacy writing or personal history. Such products may be assisted by professional or amateur genealogists, or by ghostwriters.

Memoirs are categorically written by those who are advanced enough in age, to be able to reflect appropriately. The average age for a memorist is 68.

Types of memoir

Women writers have been prominent amongst those combining the memoir form with historical non-fiction writing. Examples include Jung Chang's Wild Swans. Maxine Hong Kingston's book The Woman Warrior is an example of a memoir that combines factual material with fictional material as it tells the author's story and the story of her family.

Some professional contemporary writers such as David Sedaris and Augusten Burroughs have specialised in writing amusing essays in the form of memoirs. To some extent this is an extension of the tradition of newspaper columnists' regular accounts of their lives. (Cf. the work of James Thurber which often has a strong memoir-like content).

Another category of memoir is the eyewitness type of history by onlookers to major events or particular eras; Slave narratives (e.g. the memoirs of Frederick Douglass) fall into this category as do those by Primo Levi and Elie Wiesel.