Y/N

In emails, Y/N stands for "yes or no?" An email that starts or ends with Y/N likely contains a question to which you must answer "Yes" or "No."

For example, an email with the subject "Y/N: Are you taking the Friday after Thanksgiving off?" demands a reply of "Yes, I am taking the Friday after Thanksgiving off." or "No, I am not taking the Friday after Thanksgiving off." Y/N may be paired with VSRE, giving respondents the option to simply reply "Yes" or "No" without feeling rude or impolite.

Seasoned reader-insert fan fiction readers know that Y/N stands for "your name." When reading reader-insert fan fiction, readers are encouraged to pretend they are the story's main character. Because different readers have different names, reader-insert fan fiction often uses Y/N in place of the main character's name, allowing readers to mentally replace Y/N with their own name in dialogue and descriptions.

Reader-insert fan fiction has existed for decades but, according to Fanlore.org, the Y/N convention originated sometime around 2011. Some fanfic writers may still use a long underscore or [Name] in place of Y/N, but Y/N is now the most common substitute for a main character's name in reader-insert fan fiction.