Standard Mandarin Chinese has four main lexical tones.
In Mandarin, pitch is part of a word’s identity, not merely an expressive feature. The first tone is high and level, the second rises, the third is low or dipping, and the fourth falls sharply. Pinyin marks them with diacritics: ā, á, ǎ, and à. Changing the tone can change the meaning of an otherwise identical syllable.
Mandarin also has a neutral tone, sometimes called the fifth tone. It is lighter and shorter than the four main tones and often appears on unstressed syllables. Because it is not normally counted as a full lexical tone, general-audience quizzes conventionally answer four when asking how many tones Mandarin has.
The tones are not fixed musical notes. Their exact pitch varies with the speaker’s voice and regional accent. Tones can also change in connected speech. For example, when two third tones occur together, the first is usually pronounced like a second tone. This process is called third-tone sandhi and is one reason textbook pronunciation can differ from natural conversation.