According to, in my opinion: theo

Theo before a person or a source means "according to": Theo bác sĩ, em phải nghỉ ba ngày. According to the doctor, I have to rest for three days. It usually opens the sentence, followed by a comma.

Theo tôi means "in my opinion": Theo tôi, quán này ngon hơn. With friends, use the word you'd use for yourself: theo mình, theo em. To ask for someone's opinion, put their word after theo: Theo anh, cái nào đẹp hơn? Which one do you think looks better? Tôi nghĩ là … (I think that …) is just as common; theo tôi sounds a little more considered.

With a source, it's common in the news and on official papers: theo dự báo (according to the forecast), theo luật (by law). Theo như is a more written form: theo như kế hoạch, according to plan.

The meaning comes from the verb theo, "to follow": Đi theo tôi. Follow me. After another verb, theo means "along": Nhớ mang theo áo mưa nha. Remember to bring a raincoat.