21character

21character is a form of constrained writing in which a single piece must be exactly twenty-one characters long, counting letters, spaces, and punctuation. Variants exist that count only letters or that treat newlines differently depending on the platform.

The concept emerged in online writing communities in the late 2010s as a playful challenge within microfiction circles. It gained broader attention on social media during the early 2020s, where participants share 21-character works using tags or dedicated forums.

Practices vary by community. Some submissions consist of a single line with no title; others present a brief title followed by a 21-character body. Prompt creators may require a specific tone, theme, or alphabet constraint, and readers often vote on cleverness or clarity.

Impact and reception: Proponents argue the form trains precision and economy of language, while critics say the strict limit hinders meaningful expression.

Related concepts include constraint-based writing, microfiction, and other character-count prompts.