Need is used to talk about the things that the speaker or the listener has to do. Need can be used either as an ordinary verb or as a modal auxiliary verb.
Need as an ordinary verbWhen need is used as an ordinary verb, it takes the 鈥搒 marking when the subject is a third person singular noun or pronoun. In this case, need is followed by an infinitive with to.
He needs to mend his ways. (NOT He need to mend his ways.) (NOT He need mend his ways.) You need to find a better job. John needs to consult a doctor. I need to find a trainer. Priyanka needs to improve her communication skills.Questions are negatives are made with do.
Do I need to wait? Does he need to consult a specialist? No, he doesn鈥檛 need to consult a specialist. Does she need to come? No, she doesn鈥檛 need to come. Need as an auxiliary verbNeed can also be used as a modal auxiliary verb. When need is used as a modal auxiliary verb, the third person singular has no 鈥搒, and questions and negatives are made without do. The auxiliary need is normally followed by an infinitive without to.
The modal forms of need are only used in questions and negative sentences.
Compare:
Need we wait any longer? (Here need is used as a modal auxiliary verb and hence we make the question form without do.) No, you needn鈥檛 wait any longer. (The modal auxiliary need is followed by an infinitive without to.) Do we need to wait any longer? (Ordinary form of need) Need I water the plants? (Modal form of need) Do I need to water the plants? (Ordinary form of need) Need I pay for the call? Need I ask for his permission? No, you needn鈥檛 ask for his permission.