The auxiliary verb 要 (yào) has several different meanings, and here we'll tackle the "want to" meaning. To express "wanting to do" something, use 要 (yào) before the verb.
The verb 要 (yào) can be used as an auxiliary verb to indicate wanting to do something.
Subj. + 要 + Verb + Obj.
Tā yào xué Zhōngwén.
He wants to study Chinese.
Bǎobao yào shuìjiào.
The baby wants to sleep.
Zǎofàn wǒ yào chī ròu.
For breakfast I want to eat meat.
Jīntiān hěn lèi, wǒ yào xiūxi.
Today I'm very tired. I want to rest.
Zhège zhōumò nǐmen yào zuò shénme?
This weekend what do you want to do?
要 (yào) and 想 (xiǎng)
Instead of using 要 (yào), it is also possible to use the word 想 (xiǎng). These two words are largely interchangeable, and both can mean "to want." The small difference is that 要 (yào) is often used for something you want to or need to do, and plan to take action on. It can sound a bit more demanding (and less polite). 想 (xiǎng) on the other hand, often conveys an idea on one's mind, that one may or may not take action on. You can think of it as meaning "would like to."
Wǒ yào hē kāfēi.
I want to drink coffee.
[I am going to get my hands on some coffee.]
Wǒ xiǎng hē kāfēi.
I'd like to drink coffee.
[I want to drink a cup of coffee, but may or may not act on that.]
Nǐ yào chī shénme?
What do you want to eat?
Nǐ xiǎng chī shénme?
What would you like to eat?
[adapted from AllSet Learning Chinese Grammar Wiki, Creative Commons License BY-NC-SA 3.0]
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