声调（英语：Tone）的完整意义是指音节在发音过程中的高低抑扬性（音调，或称音高）及顿挫性（韵尾或闭塞音）。声调是依附在音节上的超音段成分。音调高低可以由阿拉伯数字的调值表示，模仿音阶1-5。调值55表示音节的调高相当于5（so），时长两拍。要准确地确定一个声调的调值，需要借助灵敏的电子仪器来记录和分析。声调不同会导致相同辅音和元音的音节和词语含义不同，此即所谓的变调时所造成之语意歧异性。

现代标准汉语不具备入声韵尾，不具顿挫性，其声调仅仅指音调的抑扬升降性。现代标准汉语包含四个声调，即阴平、阳平、上声、去声。轻声一般不当作是声调。

Tone is the use of pitch in language to distinguish lexical or grammatical meaning – that is, to distinguish or to inflect words. All verbal languages use pitch to express emotional and other paralinguistic information and to convey emphasis, contrast, and other such features in what is called intonation, but not all languages use tones to distinguish words or their inflections, analogously to consonants and vowels. Languages that do have this feature are called tonal languages; the distinctive tone patterns of such a language are sometimes called tonemes /ˈtoʊniːm/, by analogy with phoneme. Tonal languages are extremely common in Africa, East Asia, and Central America, but rare elsewhere in Asia and in Europe; as many as seventy percent of world languages may be tonal.