Phonotactic constraints

Even languages like English, which allow both onsets and codas, have restrictions on the permissible contents of those slots: these restrictions are known as phonotactic constraints. In particular, English allows clusters of two or three consonants in both onsets and codas; some languages have more complex cluster types, others only CC, and perhaps in the onset only. Some restrictions on the composition of clusters reflect structural idiosyncrasies of English; these include the examples in (2).