In linguistics, prosody (from Greek προσωδία) is the rhythm, stress, and intonation of speech. Prosody may reflect the emotional state of a speaker; whether an utterance is a statement, a question, or a command; whether the speaker is being ironic or sarcastic; emphasis, contrast and focus; and other elements of language which may not be encoded by grammar.
The details of prosody will depend upon the phonology of a language. For instance, in a language with phonemic vowel length, this must be kept distinct from prosodic syllable length. Likewise, prosodic pitch cannot obscure tone in a tone language if the result is to be intelligible. Although a tone language such as Mandarin will use pitch variations for prosody, they will occur at a different level than the pitch variations involved in lexical and grammatical tone. If pitch can be compared to ocean waves, the swells are the prosody, and the wind-blown ripples in their surface are the lexical tones. That is, the pitch corresponding to a "mid" tone may rise or fall with prosody, but it will retain its relative position compared to "high" and "low" tones. This is similar to stress in English: The word dessert has greater stress on the second syllable, compared to desert, which has greater stress on the first, but this distinction is not obscured when the entire word is stressed by a child demanding "Give me dessert!" Vowels in many languages are likewise pronounced differently (typically less centrally) in a careful rhythm or when a word is emphasized, but not so much as to overlap with the formant structure of a different vowel. Thus rhythm, loudness, pitch, and vowel formants convey a mixture of lexical and prosodic information.
Prosodic units are characterized by several phonetic cues, such as a coherent pitch contour, and the gradual decline in pitch and lengthening of vowels over the duration of the unit, until the pitch and speed are reset to begin the next unit. Breathing, both inhalation and exhalation, only seems to occur at these boundaries where the prosody resets.