All three words mean more or less the same idea. They all show that something is possible, or might be true. There is another difference, though. Maybe is the most informal of the three. You are more likely to use it while talking with your friends or family. Perhaps is neutral. You can use it in all situations and you will still sound polite. Possibly is mainly used in formal situations.
Maybe
Maybe is mainly used in informal contexts.
- Maybe we’ll go to the theater in the evening.
- Maybe I’ll drop out this year.
- Maybe we’ll take a vacation next month.
- ‘Are you going to try that steak in the cafeteria?’ ‘Hmmm…maybe.’
Perhaps
Perhaps is neutral. It can be used in both formal and informal contexts.
- Perhaps we will make another attempt.
- There were 200, perhaps 250, students in the auditorium.
- Her latest movie is perhaps her best.
Possibly
Possibly is mainly used in formal contexts.
- ‘Do you think she will marry him?’ ‘Hmm. Possibly not.’
- I may possibly accept that job.
- ‘Do you have enough money to buy a drink?’ ‘Possibly’. (=I think so; I am not exactly sure.)
Quite possibly / very possibly
These expressions are used to indicate a greater possibility of something happening.
- She is quite possibly the most deserving candidate.
- How can anyone possibly spend 30 years in prison?
- We have done everything we could possibly do.
Possibly can be used in very polite requests.
- Could you possibly help me in the kitchen?