The Mandarin Chinese particle de (的) is most commonly used as a possessive modifier. It can be used between two nouns to indicate a relationship of possessor / possession.
Wǒ de péngyou.
Notice that de is used after the first (pro)noun. This gives us the following possessive pronouns:
Mine – wǒ de
Yours – nǐ de
His – tā de
Hers – tā de
Theirs – tāmen de
Ours – wǒmen de
The de particle can be used for any possessive noun or pronoun, such as “Miss Chen’s pen” (Chén xiǎojie de bǐ), or “American schools” (Měiguó de xuéxiào).
The de particle can also used in describing objects or people. “Big chair” is dà de yǐzi. In this usage de follows the adjective.
lánsè de yīfu
yìdàlì de chē zǐ
The de particle is sometimes used for emphasis or affirmation.
Wǒ huì qù de!
I am going!
Shàngkè, yào zhuānxīn de.
When you are in class, you have to concentrate.