Tones 聲調（声调）

Chinese is a tonal language. This means the pitch or tone in which a sound is said affects the meaning.

In Mandarin Chinese, there are four basic tones and a fifth neutral tone. Each syllable in each word has one of these tones.

You can tell which tone to give a syllable from by the marks above the vowels in pinyin 

Tone	Mark	Description
The first tone (or high-level tone) 阴平		The first tone is high and level. It is important to keep one's voice even (almost monotone) across the whole syllable when pronouncing the first tone. It is represented by a straight horizontal line above a letter in pinyin (or sometimes by a number "1" written after the syllable).
The second tone (or rising tone) 阳平		The second rises moderately. In English we sometimes associate this rise in pitch with a question. The second tone is represented by a rising diagonal line above a letter in pinyin (or sometimes by a number "2" written after the syllable).
The third tone (or falling-rising tone) 上声		The third tone falls and then rises again. When pronounced clearly, its tonal "dipping" is very distinctive. It is represented by a curved "dipping" line above a letter in pinyin (or sometimes by a number "3" written after the syllable).
The fourth tone (or falling tone) 去声		The fourth tone starts out high but drops sharply to the bottom of the tonal range. English-speakers often associate this tone with an angry command. It is represented by a dropping diagonal line above a letter in pinyin (or sometimes by a number "4" written after the syllable).
Neutral Tone 轻声		The neutral tone is not mapped on the tone chart because it differs from the other four tones in that it does not have a defined pitch contour. The neutral tone is pronounced quickly and lightly without regard to pitch. Syllables with a neutral tone have no tone mark (but are sometimes marked with a "5" or a "0" after the syllable). This tone is usually very easy to pick up. Note that aside from grammatical particles, single syllable words cannot have a neutral tone.