Will is a modal verb used to indicate future time. For example:
- It will be sunny tomorrow.
- The new restaurant will open next week.

Will comes after the subject and before the main verb, and in questions the subject and will invert. Will often contracts to 'll, for example he'll, they'll, and in negatives will not often contracts to won't.

He will / He'll stay at home tomorrow.
They will / They'll be very busy.

I will not / won't stay at home tomorrow.
They will not / won't be very busy.

Will he stay at home tomorrwo?
Will they be busy?

Will is used for future predictions and facts. For example:
- We'll finish it by tonight.
- We have a lot of time. We won't be late.
- "Where will you go next year?" "I'll go to America."

Will is also used to make a spontaneous response. For example:
Offer: - "The telephone's ringing." "I'll answer it."
Promise: - "I'll never leave you" - "I'll give it to you tomorrow morning."
Request: - "Will you wait for me this evening?"
Will for requests is quite strong and often used when the expected answer is "Yes". Otherwise can is more polite: "Can you wait for me this evening?"
Threat: - "You'll be sorry!"
Order: - "You will not eat my chocolate-chip cookies!"

Shall

Shall is used with only I and we to make questions. For example:
"Shall I open the window?"

It can also be used to make statements, but this is formal and old-fashioned.
"We shall arrive at 6.00."

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