Accent (/, /) is the phonetic prominence given to a particular syllable in a word, or to a particular word within a phrase. When this prominence is produced through greater dynamic force, typically signaled by a combination of amplitude (volume), syllable or vowel length, full articulation of the vowel, and a non-distinctive change in pitch, the result is called stress accent, dynamic accent, or simply stress. When it is produced through pitch alone, it is called pitch accent (although this term is often used with a somewhat different meaning; see below). When it is produced through length alone, it is called quantitative accent. English has stress accent.
A prominent syllable or word is said to be accented or tonic; the latter term does not imply that it carries phonemic tone. Other syllables or words are said to be unaccented or atonic. Syllables are frequently said to be in pretonic or post-tonic position; certain phonological rules apply specifically to such positions. For instance, in American English, /t/ and /d/ are flapped in post-tonic position.
In some languages, accented syllables have the typical features of stress accent as listed above, except that the change in pitch on such syllables may be distinctive; that is, an accented syllable may carry more than one possible tone (and differences in tone sometimes distinguish words), whereas unaccented syllables do not carry tone. An example of this is Serbo-Croatian accent. The term pitch accent is frequently used to denote accent systems of this type (in spite of inconsistency with the definition of this term given above).