Chinese is a tone language. It has four basic tones, which are indicated respectively by the tone marks:ˉ (first tone) 阴,ˊ (second tone) 阳,ˇ (third tone) 上, andˋ (fourth tone)去.
There is also a neutral, so-called “fifth tone”, which is unstressed and goes unmarked.

The tones are used to distinguish meanings of a syllable. Syllables with different tones have different meanings. Table below shows the example of five characters whose pronunciations differ only in their tones:

Syllable/Word	Pronunciation	Meaning	Description of tone
mā 妈		Mother	Flat or High Level Tone
má 麻		hemp	Rising or High-Rising Tone
mǎ 马		Horse	Falling-Rising or Low Tone
mà 骂		To curse	Falling or High-Falling Tone
ma 吗		Question particle	When a syllable has no tone mark exists, it is called Neutral Tone and is pronounced both light and short.

Diagram below illustrates the relative pitch changes of the four tones

Rules for placing the tone mark

When there is only one vowel in a syllable, the tone mark is put above the vowel.
An algorithm to find the correct vowel letter (when there is more than one) is as follows:
- – If there is an “a” or an “e”, it will take the tone mark.
- – If there is an “ou”, then the “o” takes the tone mark.
- – Otherwise, the second vowel takes the tone mark.
If the tone is written over an “i”, the dot above the “i” is omitted, as in “yī”.

Interesting Chinese “song” that illustrates the rules well:

有 a 不放过	If there is an “a” in the Pinyin, it will take the tone mark. eg: lai mark at “a” as lài
无 a 找 o, e	If there is no “a” in the Pinyin, look for “o” or “e”. eg: lou, mark at “o” as lóu; and lei mark at “e” as lèi
i, u 并列标在后	If “i” and “u” exist together，mark at the behind one. eg: liu, mark at “u” as liú ；gui, mark at “i” as guì
单个韵母不必说	If there is only 1 vowel, mark at the only vowel