Need is used both as an auxiliary verb and as an ordinary verb. As an ordinary verb, need is used in the sense of require.
- I need help.
- We need more people to finish the work.
- I need some more time to decide the question.
The auxiliary need is commonly used with not. It is followed by an infinitive without to.
- You need not wait for me. (NOT You need not to wait for me.)
- They need not make such a fuss over it.
The auxiliary need does not take the marking -s in the third person singular.
- He need not wait any longer. (NOT He needs not wait any longer.)
The auxiliary need is sometimes used with hardly.
- We need hardly remind you of your promise to visit us.
- I need hardly add that I am very grateful.
The auxiliary need can be used with only.
- You need only say what you want and it will be granted.
In questions need is usually used without not.
- Need I wait any longer?
- Need I come again?
If the answer is in the negative you may say, ‘No, you need not’ or ‘No, he need not’. If the answer is in the positive you should say – ‘Yes, he must’ or ‘Yes, you must’.
When referring to past time, need is followed by the perfect infinitive.
- You need not have lost your temper.
- We need not have waited for them.