Click consonants, or clicks, are speech sounds that occur as consonants in many languages of Southern Africa and in three languages of East Africa. Examples familiar to English-speakers are the tut-tut (British spelling) or tsk! tsk! (American spelling) used to express disapproval or pity (IPA [ǀ]), the tchick! used to spur on a horse (IPA [ǁ]), and the clip-clop! sound children make with their tongue to imitate a horse trotting (IPA [ǃ]). However, these paralinguistic sounds in English are not full click consonants, as they only involve the front of the tongue, without the release of the back of the tongue that is required for clicks to combine with vowels and form syllables.

Anatomically, clicks are obstruents articulated with two closures (points of contact) in the mouth, one forward and one at the back. The enclosed pocket of air is rarefied by a sucking action of the tongue (in technical terminology, clicks have a lingual ingressive airstream mechanism). The forward closure is then released, producing what may be the loudest consonants in the language, although in some languages such as Hadza and Sandawe, clicks can be more subtle and may even be mistaken for ejectives.

Click consonants occur at six principal places of articulation. The International Phonetic Alphabet (IPA) provides five letters for these places (there is as yet no dedicated symbol for the sixth).

The above clicks sound like affricates, in that they involve a lot of friction. The next two families of clicks are more abrupt sounds that do not have this friction.

Technically, these IPA letters transcribe only the forward articulation of the click, not the entire consonant. As the Handbook states,

Since any click involves a velar or uvular closure [as well], it is possible to symbolize factors such as voicelessness, voicing or nasality of the click by combining the click symbol with the appropriate velar or uvular symbol: [k͡ǂ ɡ͡ǂ ŋ͡ǂ], [q͡ǃ].

Thus technically [ǂ] is not a consonant, but only one part of the articulation of a consonant, and one may speak of "ǂ-clicks" to mean any of the various click consonants that share the [ǂ] place of articulation. In practice, however, the simple letter ⟨ǂ⟩ has long been used as an abbreviation for [k͡ǂ], and in that role it is sometimes seen combined with diacritics for voicing (e.g. ⟨ǂ̬⟩ for [ɡ͡ǂ]), nasalization (e.g. ⟨ǂ̃⟩ for [ŋ͡ǂ]), etc. These differing transcription conventions may reflect differing theoretical analyses of the nature of click consonants, or attempts to address common misunderstandings of clicks.

Clicks occur in all three Khoisan language families of southern Africa, where they may be the most numerous consonants. To a lesser extent they occur in three neighbouring groups of Bantu languages—which borrowed them, directly or indirectly, from Khoisan. In the southeast, in eastern South Africa, Eswatini, Lesotho, Zimbabwe and southern Mozambique, they were adopted from a Tuu language (or languages) by the languages of the Nguni cluster (especially Zulu, Xhosa and Phuthi, but also to a lesser extent Swazi and Ndebele), and spread from them in a reduced fashion to the Zulu-based pidgin Fanagalo, Sesotho, Tsonga, Ronga, the Mzimba dialect of Tumbuka and more recently to Ndau and urban varieties of Pedi, where the spread of clicks continues. The second point of transfer was near the Caprivi Strip and the Okavango River where, apparently, the Yeyi language borrowed the clicks from a West Kalahari Khoe language; a separate development led to a smaller click inventory in the neighbouring Mbukushu, Kwangali, Gciriku, Kuhane and Fwe languages in Angola, Namibia, Botswana and Zambia. These sounds occur not only in borrowed vocabulary, but have spread to native Bantu words as well, in the case of Nguni at least partially due to a type of word taboo called hlonipha. Some creolised varieties of Afrikaans, such as Oorlams, retain clicks in Khoekhoe words.