Greetings to all the readers!! This particular mistake is a common one, even fluent English speakers do that sometimes. If you talk to someone, you are the first person and the person you talk to is the second person. Suppose your conversation is about another person or things, that is called as third person. To be frank, all these terms were like latin(something unknown) words to me till i complete my graduation 10 years back. If your discussion is about a single person or thing, about the current event, and it is time to you use 's' with verb. Example He walks. She runs. It sleeps. It rains and so on. what if your sentence is negative or question, then Negative He does not walk. She does not run. It does not sleep. Yes or No Question Does he walk? Does she run? Does it sleep? WH Question Where does he walk? When does she run? How does it sleep?