Write What You Know

Many shows, books, movies, and other media that depict a real-world activity (police procedures, military procedures, wilderness survival—hell, even hobbies like playing video games)—often get it totally wrong, with plenty of glaring flaws that anyone who has engaged in that activity could quickly point out. If you're not careful, you might even get Falsely Advertised Accuracy.

Some people avoid this problem by Doing the Research, and some even go so far as to Show Their Work, going out of their way to show off facts that they learned while researching the activity.

But some people don't need to Do the Research, because they already know. It's their life. The story they tell is their former profession. The world they build in the work of fiction is the world they actually grew up in.

This is because some writers write what they know. And if they know their subject well, this puts them in a unique position that gives them an advantage over people who would have to go out of their way to research the subject instead. A police officer who writes novels on the side can depict police procedure and what goes on in the department realistically. Someone who has to research it second-hand might be able to as well, but will still be missing the life experiences that the actual officer would have. Same with any other profession.

A writer who has primarily worked as a professional writer can also do this, but it results in Most Writers Are Writers. (Ever wonder why so many characters in fiction are authors, screenwriters, or journalists? That's why.)

See also Write Who You Know, for when writers grab from their circle of family and acquaintances to create their characters. Can also pop up in Written for My Kids, where an author writes a work specifically with their own child or children in mind.

Note: This is NOT just about people who write about their current interest or hobby, but instead is about whether or not the interest or hobby is depicted very realistically because the author does it for a living or grows up around it, etc. If it is, then it's Write What You Know. If it isn't depicted realistically, then they're no different from any other author. For when the author writes about something because it speaks to them, regardless of how much they know about it, see Author Appeal.

As this trope is often also used (and misused) as a piece of writing advice, it should perhaps be noted that Tropes Are Tools, and that Writing What You Know is not an ironclad rule which automatically guarantees that you will produce superior work over someone lacking that experience. Having first-hand experience of what you're writing about may give you an advantage over someone who does not have the same experience when it comes to research and life experience, but that doesn't automatically mean that you will also possess superior writing skills. Nor does it mean that someone who must rely on second-hand research instead of life experience cannot effectively write a story set in a world that they are unfamiliar with. Finally, it doesn't mean that someone cannot convincingly write, say, a Science Fiction or Fantasy story set in other worlds involving creatures and experiences that are a bit thin on the ground. The idea is that a writer can draw on their own personal experiences to inform their story and give it life and verisimilitude, not that the writer can only write about things that they have direct personal first-hand experience of.

This said, as the page quote suggests, if you don't know about something you intend to write about it's usually a good idea to find out more about it somehow, if only to make sure you avoid any glaring errors.

Compare I Should Write a Book About This, when a character in-story realizes that their experiences might make a good book. Author Avatar is when a writer goes the whole way and writes about a thinly fictionalized version of themselves.

Real Life examples: