A tonal language is a language in which differences in tone are distinctive. In a tonal language, two words with the same segmental phonemes but different intonations usually have different meanings. In the simplest case, two or three level tones are distinguished (high/low resp. high/mid/low). Many tonal languages also have contour tone, i.e. rising, falling, rising-falling or falling-rising.
Examples of tonal languages are Chinese and many other East Asian languages, and most African languages.