How to know when I should add 안 in a sentence? I'm currently on Rosetta Stone to learn Korean and I'm on Level 1, Lesson 2, in the Grammar section. At first, 안 was used in this sentence,  남 자아이가  운전을  (안)  해 요.*  *Placed in parentheses to point it out. Opposed to this sentence, 남자가 운 전 을 해요. At first, I thought that the difference was that the first sentence was for a child sitting, and the second sentence was for an adult sitting, but then it was used for a group of adults standing together. 사람들이 수영을 (안) 해요. * Yet, there was an image of a group of adults swimming, which didn't use the term. It began to confuse me on when I should add the term in a sentence. Can you inform me on how I'm suppose to use the term and when I should add it? Please and thank you in advanced.