Katakana (片仮名、カタカナ, IPA: [katakaꜜna, kataꜜkana]) is a Japanese syllabary, one component of the Japanese writing system along with hiragana, kanji and in some cases the Latin script (known as rōmaji).

The word katakana means "fragmentary kana", as the katakana characters are derived from components or fragments of more complex kanji. Katakana and hiragana are both kana systems. With one or two minor exceptions, each syllable (strictly mora) in the Japanese language is represented by one character or kana in each system. Each kana represents either a vowel such as "a" (katakana ア); a consonant followed by a vowel such as "ka" (katakana カ); or "n" (katakana ン), a nasal sonorant which, depending on the context, sounds either like English m, n or ng ([ŋ]) or like the nasal vowels of Portuguese or Galician.

In contrast to the hiragana syllabary, which is used for Japanese words not covered by kanji and for grammatical inflections, the katakana syllabary usage is comparable to italics in English; specifically, it is used for transcription of foreign-language words into Japanese and the writing of loan words (collectively gairaigo); for emphasis; to represent onomatopoeia; for technical and scientific terms; and for names of plants, animals, minerals and often Japanese companies.

Katakana evolved from Japanese Buddhist monks transliterating Chinese texts into Japanese.