Subject + 认识 + Person
The verb 认识 (rènshi) means "to know" someone or "to recognize" and refers specifically to being acquainted with a person. It differs from 知道, which means to know a fact. You can say 我认识你 (I know you) to express familiarity with someone.
我认识他很多年了。
Wǒ rènshi tā hěn duō nián le.
I've known him for many years.
你认识那个穿红衣服的人吗?
Nǐ rènshi nàge chuān hóng yīfu de rén ma?
Do you know the person wearing red?
我们是在大学认识的。
Wǒmen shì zài dàxué rènshi de.
We met in college.