ふ, in hiragana, or フ in katakana, is one of the Japanese kana, each of which represents one mora.

It represents the phoneme /hɯ/, although for phonological reasons (general scheme for /h/ group, whose only phonologic survivor to /f/ ([ɸ]) remaining is ふ: b←p←f→h), the actual pronunciation is [ɸɯᵝ] ⓘ, which is why it is romanized fu in Hepburn romanization instead of hu as in Nihon-shiki and Kunrei-shiki rōmaji (Korean 후 /hu/ creates the same phonetic effect as lips are projected when pronouncing "u").

The katakana フ is frequently combined with other vowels to represent sounds in foreign words.

For example, the word "file" is written in Japanese as ファイル (fairu), with ファ representing a non-native sound, fa.

[1] In the Ainu language the katakana with a handakuten プ can be written as a small ㇷ゚ to represent a final p sound.