In the Japanese language, the gojūon (五十音, Japanese pronunciation: [ɡo(d)ʑɯꜜːoɴ], lit. "fifty sounds") is a traditional system ordering kana characters by their component phonemes, roughly analogous to alphabetical order. The "fifty" (gojū) in its name refers to the 5×10 grid in which the characters are displayed. Each kana, which may be a hiragana or katakana character, corresponds to one sound in Japanese. As depicted at the right using hiragana characters, the sequence begins with あ (a), い (i), う (u), え (e), お (o), then continues with か (ka), き (ki), く (ku), け (ke), こ (ko), and so on and so forth for a total of ten rows of five columns.

Katakana is a Japanese syllabary, one component of the Japanese writing system along with hiragana, kanji and in some cases the Latin script.