Example:
Oh, I left the door open. I'll go and shut it.

In spoken English, the negative of will is usually won't (=will not):

Example: I can see you're busy, so I won't stay long.

B. Do not use will to talk about what you have already decided or arranged to do.

Examples:
I'm leaving on vacation next Saturday. (not I'll leave)
Are you working tomorrow? (not Will you work)

C. We often use will in these situations:
Offering to do something

Example:
That looks heavy. I'll help you with it.

Agreeing to do something
Example:
Of course, I'll give it to you this afternoon.

Promising to do something
Example:
I won't tell anyone what happened. I promise.

Asking somebody to do something
Example:
Will you shut the door, please?

D. Shall I...? Shall we...?

Shall is used in the questions Shall I..?/Shall we..? to ask somebody's opinion.
Example:?
Shall I open the window?

We also use should in the same situations.
Example:?
Should I open the window?

WILL (2)

"I'll be inviting Hannah this Saturday. But she'll probably be busy. But I'll take my chances. I guess I'll just have to hope that she will not be doing anything on that day."

A. We do not use will to say what somebody has already arranged or decided to do in the future:
Examples:
Tricia is working next week. (not Tricia will work)
When will you find out how you did on the exam?

B. We often use will ('ll) with: