On the literary genre spectrum, memoirs and autobiographies are right next to each other. They’re both nonfiction accounts of the author’s personal experience, usually written in first person (i.e. using I, me, and other first-person pronouns). But despite their similarities—and the fact that memoir and autobiography are often used interchangeably—they’re technically separate genres.

Since an autobiography is essentially just a biography written by the person it’s about, it has pretty much all the characteristics of a regular biography. As MasterClass explains, the narrative typically progresses chronologically and covers the subject’s whole life (thus far), with a focus on facts. That’s not to say autobiographies by default have bare-bones prose or a lack of emotion—the story of someone’s life will likely feature some fascinating formative memories and the feelings that came with them.

But those elements are much more integral to a memoir than an autobiography. According to Book Riot, a memoir doesn’t usually cover the author’s entire life, but instead a specific period or themes within it. Joan Didion’s The Year of Magical Thinking, for example, centers on the year after her husband, John Gregory Dunne, died of a heart attack in late 2003. It’s just as much a discourse on grief as it is an account of what happened in Didion’s life that year—and you might pick it up to read about grief rather than to learn about the author herself. Though Didion was, by that point in her career, famous enough that people would be interested to read about her experiences in particular, that’s not always the case with memoirists. Sometimes, it’s the subject matter that attracts readers, not the name of the author.

If you crack open an autobiography, on the other hand, it’s probably because you want to learn about the person who wrote it. Autobiographers are usually celebrities, from activists like Malala Yousafzai and Nelson Mandela to athletes like Andre Agassi—people who’ve achieved such success and/or have lived such high-profile lives that you’d want to read their full stories, starting from the cradle.

All that said, the differences between memoirs and autobiographies are more general trends than definitive guidelines. There’s no rule that says your memoir can’t be chronological, or that your autobiography must include your year and place of birth in order to be considered a true autobiography.

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