We use Future Simple to talk about
- On-the-spot spontaneous decisions (at the moment of speaking), unplanned actions
Oh, is it Tom’s birthday today? I’ll call him!
+Actions in the future we are not sure about, possible actions. (We use I think, Maybe, I hope, Perhaps etc.)
Maybe I’ll go to the cinema today. But I’m not sure.
- Predictions about the future (based on what we think or believe)
I think it’ll be a great party!
Will + V1
I will call you./ I’ll call you.
He will open the door./He’ll open the door.
They will arrive late./ They’ll arrive late.
I won’t call you.
He won’t open.
Will + subject + V1
Will you call me?
Will he open the door?