müssen

1. Gebot Verpflichtung

1.1. must + verb You must be home by 8.

1.2. have to / has to / had to + verb They had to help on the fields.

1.3. to be to + verb We are to be back by ten p.m.

1.4. nicht dürfen (Verbot)

1.4.1. must not Hurry up! We mustn't be late!

1.4.2. am/is/are (was/were) not allowed to We were not allowed to stay out late.

1.4.3. not to be to + verb You are not to leave the house without permission. Is that clear?

2. Notwendigkeit

2.1. need to + verb I need to go to the toilet.

2.2. nicht brauchen (nicht notwendig)

2.2.1. don't / doesn't / didn't have to + verb We don't have to do the dishes.

2.2.2. need not + verb You needn't wait for me. I'll join you later.