In order to: để

Để before a verb says what something is for, like "to" or "in order to": Tôi học tiếng Việt để nói chuyện với ba mẹ vợ. I'm learning Vietnamese to talk with my wife's parents. The action comes first, then để, then the purpose.

When the purpose involves someone else, put that person after để, like "so that": Anh nói chậm một chút để em hiểu. Speak a bit more slowly so I can follow.

After a verb of going, such as đi, ra or về, để is usually left out, and the two verbs just follow each other: Em ra chợ mua rau. I'm going to the market to buy vegetables.

Để can also open the sentence, to put the purpose first. This is more common in writing and careful speech: Để nói giỏi, mình phải nói mỗi ngày. To speak well, you have to speak every day.

Two look-alikes: để làm gì? asks "what for?", and để with a person after it, at the start of a sentence, usually means "let": Để em giúp chị. Let me help you. And để is also an everyday verb for "put, leave": Em để chìa khóa ở đâu? Where did you put the key?