We use Future Simple to talk about

  1. 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.

  1. 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.

Negative –

Will not/won’t

I won’t call you.

He won’t open.

Question ?

Will + subject + V1

Will you call me?

Will he open the door?