The future simple (sometimes called just ‘will’) is used for many reasons. We'll explore them more below.
But first, its form is:
S (I/You/They etc.) + will/will not
1). We use will to make predictions about the future:
It will be sunny tomorrow afternoon; Tottenham will win the league; Germany will not go into a recession next year
2). Or to find out information about the future:
Will everyone be at the event tomorrow?; will you be calm when you’re doing the presentation?
3). Whereas British English sometimes uses shall/shan’t instead of will/won’t (will not), American English uses will and won’t/will not only:
I shall not go to the park – I will not/won’t go to the park
We shall eat dinner together tomorrow night – We will eat dinner together tomorrow night
4). We also use will in conditionals:
If it’s cold tomorrow, I will wear a coat; If Tom is angry tomorrow, I’ll just ignore him; Don’t be so boring. I’ll have to liven you up!
5). And to make polite requests, an offer, order, or a threat:
Shall I help you with the shopping?; I’ll break him!; I’ll pay you 50 bucks and you’ve got a deal
6). When making a decision in that moment, ‘will’ is more appropriate than ‘going to’.
I’ll sell the car (decided there and then)
I’m going to sell the car (already decided)
But when a time is put into the sentence, the present progressive can be used to express arrangements and plans. Will cannot be used for plans and arrangements, but ‘going to do something’ can:
We’re having dinner together on Thursday; I’m travelling to Vietnam next Saturday; What are we going to do tomorrow?
7). Will can also be used in formal orders and usually demonstrates the speaker is in an authoritative position:
You will arrive at 10am tomorrow; Colleagues will exit the building through the fire exit