An affricate is a consonant that begins as a stop and releases as a fricative, generally with the same place of articulation (most often coronal). It is often difficult to decide if a stop and fricative form a single phoneme or a consonant pair. English has two affricate phonemes, /t͡ʃ/ and /d͡ʒ/, often spelled ch and j, respectively.
The English sounds spelled "ch" and "j" (broadly transcribed as [t͡ʃ] and [d͡ʒ] in the IPA), German and Italian z [t͡s] and Italian z [d͡z] are typical affricates, and sounds like these are fairly common in the world's languages, as are other affricates with similar sounds, such as those in Polish and Chinese. However, voiced affricates other than [d͡ʒ] are relatively uncommon. For several places of articulation they are not attested at all.
Much less common are labiodental affricates, such as [p͡f] in German and Izi, or velar affricates, such as [k͡x] in Tswana (written kg) or in High Alemannic Swiss German dialects. Worldwide, relatively few languages have affricates in these positions even though the corresponding stop consonants, [p] and [k], are common or virtually universal. Also less common are alveolar affricates where the fricative release is lateral, such as the [t͡ɬ] sound found in Nahuatl and Navajo. Some other Athabaskan languages, such as Dene Suline, have unaspirated, aspirated, and ejective series of affricates whose release may be dental, alveolar, postalveolar, or lateral: [t̪͡θ], [t̪͡θh], [t̪͡θʼ], [t͡s], [t͡sh], [t͡sʼ], [t͡ʃ], [t͡ʃh], [t͡ʃʼ], [t͡ɬ], [t͡ɬh], and [t͡ɬʼ].
Affricates are transcribed in the International Phonetic Alphabet by a combination of two letters, one for the stop element and the other for the fricative element. In order to show that these are parts of a single consonant, a tie bar is generally used. The tie bar appears most commonly above the two letters, but may be placed under them if it fits better there, or simply because it is more legible. Thus:
p͡f, t͡s d͡z, t͡ɬ d͡ɮ, t͡ʃ d͡ʒ, t͡ɕ d͡ʑ, ʈ͡ʂ ɖ͡ʐ , k͡x
or
p͜f, t͜s d͜z, t͜ɬ d͜ɮ, t͜ʃ d͜ʒ, t͜ɕ d͜ʑ, ʈ͜ʂ ɖ͜ʐ , k͜x.