Need(n’t), don’t need to and don’t have to

1. need = an ordinary or a modal verb

1.1. in questions

1.1.1. rarely in affirmative sentences

1.1.1.1. sometimes in written English

1.2. as a modal verb in negative sentences

1.2.1. with negative words: hardly, never, nobody, no one, only

2. needn’t = to give permission not to do smth

2.1. needn’t: apply, concern, fear, involve, mean, panic

3. needn’t or don’t have to

3.1. unnecessary to do smth

3.1.1. is not necessarily true