Katakana has a very different birthplace than hiragana. Buddhist monks studying Chinese scripture needed a fast way to mark Japanese pronunciation and grammar notes directly in the margins of dense classical texts — there wasn't room for full cursive script, so they abbreviated man'yōgana kanji down to small angular fragments, often just a single corner or radical of the original character. That clipped, efficient shorthand became katakana.

Because of its origins in formal religious and scholarly annotation, katakana carried a more official, serious connotation for centuries, while hiragana was associated with personal and literary writing. That hierarchy has completely flipped in modern usage: today katakana's most common job is spelling out loanwords from other languages, scientific and technical terms, onomatopoeia, and anything a writer wants to set apart for emphasis — doing for Japanese roughly what italics do in English.