should is a suggestion. must a more individual rule to follow, whereas "have to" a general rule is. Pay also attention that must does not have a future/past tense. You have to (^^) use "have to": You must do your homework! = I had to do my homework. Since I am not sure whether you ask for English or German...here the same for German: must/have to = müssen (a command - ein Befehl) Kinder müssen in die Schule gehen = Children have to go to school. Sie muss ihr Zimmer aufräumen = She must clean her room. In a more formal and old-fashioned way, German has also the "haben"-structure: Er hat dies zu tun. = He has to do it. In colloquial German this is usually not used. should sollen = suggestion - ein Vorschlag He should go to the doctor = Er sollte zum Arzt gehen. We can emphasize in German more than in English by using also "Konjunktiv": Er soll zum Arzt gehen Er sollte zum Arzt gehen. The first sounds more like a command. Actually, it is one. But weaker than "Geh zum Arzt!". The second is more a suggestion. You will find "man soll/sollte" in many talks and texts. It is a very colloquial expression, and sounds a little unimaginative and "uneducated". You should avoid it. You will find such expressions like: "Man sollte dies hier drücken. Man sollte dies öffnen". You should clearly state what you want: "Drücken Sie den Knopf!" or "Öffne dies hier"...

Is this a question about German or English? The title says For learing German, but the question seems to be about English.

Must - very important(sometimes for rules) Should - a good idea Have to - it's necessary So your questions aren't the same! It depends on what you want to say!