Kaph (also spelled kaf) is the eleventh letter of the Semitic abjads, including Phoenician kāp 𐤊, Hebrew kāp̄ כ‎, Aramaic kāp 𐡊, Syriac kāp̄ ܟ, and Arabic kāf ك‎ (in abjadi order). It is also related to the Ancient North Arabian 𐪋‎, South Arabian 𐩫, and Ge'ez ከ.

The Phoenician letter gave rise to the Greek kappa (Κ), Latin K, and Cyrillic К.

Kaph is thought to be derived from a pictogram of a hand (in both modern Arabic and modern Hebrew, kaph כף means "palm" or "grip"), though in Arabic the a in the name of the letter (كاف) is pronounced longer than the a in the word meaning "palm" (كَف). The small ک above the kāf in its final and isolated forms ⟨ك  ـك⟩ was originally ‘alāmatu-l-ihmāl, but became a permanent part of the letter. Previously this sign could also appear above the medial form of kāf, instead of the stroke on its ascender.

The letter is named kāf, and it is written in several ways depending on its position in the word.

There are four variants of the letter:

Other than the four variants of the letter kāf as mentioned below, there are also five other variants of the Persian letter gaf, namely,

In Ottoman Turkish, Chagatai, Kazakh, Kyrgyz, Azerbaijani, Uyghur, Moroccan Arabic, Xiao'erjing script, the Arabic letter ng has two forms, namely:

There is also one another variant of the letter ng, which is the letter khe with three dots below, and it is thus written as: