Expressing Possibility: may, might, could
Use may, might, or could to say that something is possible in the future — you are not sure if it will happen. All three are followed by the base verb.
I might still be at home with my parents next year. (possible, not sure)
You could live with a friend. (possible option)
You may find something cheap outside the city. (possible)
She might not come to the party. (possibly won't happen)
Expressing Near Certainty: probably
Use probably when you are almost sure something will or won't happen. Place probably after will in positive sentences, and before won't in negative sentences.
I will probably get a new job next year. (almost certain — positive)
I probably won't have enough money for that. (almost certain — negative)
She will probably be late.
Expressing Full Certainty: definitely
Use definitely when you are completely sure something will happen. Place definitely after will in positive sentences, and before won't in negative sentences.
I will definitely miss them! (100% certain — positive)
He definitely won't forget your birthday. (100% certain — negative)
💡 Certainty scale:
could / may / might → possible (maybe 30–50%)
will probably → almost certain (around 70–80%)
will definitely → completely certain (100%)
⚠ Common mistakes:
✗ She might to come tomorrow. → ✓ She might come tomorrow. (no to after modals)
✗ I will go definitely. → ✓ I will definitely go. (definitely goes between will and the verb)
✗ I probably won't to pass. → ✓ I probably won't pass.