Gh is a digraph found in many languages.

In English, ⟨gh⟩ historically represented [x] (the voiceless velar fricative, as in the Scottish Gaelic word loch), and still does in lough and certain other Hiberno-English words, especially proper nouns. In the dominant dialects of modern English, ⟨gh⟩ is almost always either silent or pronounced /f/ (see Ough). It is thought that before disappearing, the sound became partially or completely voiced to [ɣx] or [ɣ], which would explain the new spelling — Old English used a simple ⟨h⟩ — and the diphthongization of any preceding vowel.

Alexander John Ellis reported it being pronounced as [x] on the Yorkshire-Lancashire border and close to the Scottish border in the late nineteenth century.

It is also occasionally pronounced [ə], such as in Edinburgh as well as [θ] in Keighley.

When gh occurs at the beginning of a word in English, it is pronounced /ɡ/ as in "ghost", "ghastly", "ghoul", "ghetto", "ghee" etc. In this context, it does not derive from a former /x/.

American Literary Braille has a dedicated cell pattern for the digraph ⟨gh⟩ (dots 126, ⠣).

In Middle Dutch, ⟨gh⟩ was often used to represent /ɣ/ (the voiced velar fricative) before ⟨e⟩, ⟨i⟩, and ⟨y⟩. This usage survives in place names such as Ghent.

The spelling of English word ghost with a ⟨gh⟩ (from Middle English gost) was likely influenced by the Middle Dutch spelling gheest (Modern Dutch geest).