Future Simple

The Future Simple tense is often called the "will tense" because we make the Future Simple with the modal auxiliary will.

How do we make the Future Simple tense?

The structure of the Future Simple tense is:

subject	+	auxiliary will	+	main verb
		invariable		base
		will		V1

For negative sentences in the Future Simple tense, we insert not between the auxiliary verb and main verb. For question sentences, we exchange the subject and auxiliary verb. Look at these example sentences with the Future Simple tense:

	subject	auxiliary verb		main verb
+	I	will		open	the door.
+	You	will		finish	before me.
-	She	will	not	be	at school tomorrow.
-	We	will	not	leave	yet.
?	Will	you		arrive	on time?
?	Will	they		want	dinner?

We sometimes use shall instead of will, especially for I and we.

Contraction with Future Simple

When we use the Future Simple tense in speaking, we often contract the subject and auxiliary verb:

I will	I'll
you will	you'll
he will she will it will	he'll she'll it'll
we will	we'll
they will	they'll

In negative sentences, we contract with won't, like this:

I will not	I won't
you will not	you won't
he will not she will not it will not	he won't she won't it won't
we will not	we won't
they will not	they won't

How do we use the Future Simple tense?

No Plan

We use the Future Simple tense when there is no plan or decision to do something before we speak. We make the decision spontaneously at the time of speaking. Look at these examples:

• Hold on. I'll get a pen.
• We will see what we can do to help you.
• Maybe we'll stay in and watch television tonight.

In these examples, we had no firm plan before speaking. The decision is made at the time of speaking.
We often use the Future Simple tense with the verb to think before it:

• I think I'll go to the gym tomorrow.
• I think I will have a holiday next year.
• I don't think I'll buy that car.

Prediction

We often use the Future Simple tense to make a prediction about the future. Again, there is no firm plan. We are saying what we think will happen. Here are some examples:

• It will rain tomorrow.
• People won't go to Jupiter before the 22nd century.
• Who do you think will get the job?

Be

When the main verb is be, we can use the Future Simple tense even if we have a firm plan or decision before speaking. Examples:

• I'll be in London tomorrow.
• I'm going shopping. I won't be very long.
• Will you be at work tomorrow?

https://www.englishclub.com/grammar/verb-tenses_future.htm