Simple future, form
The 'simple' future is composed of two parts: will / shall + the infinitive without 'to'

NOTE: The form 'it will' is not normally shortened.                                     

Example: to see, simple future

*NOTE: shall is slightly dated but can be used instead of will with I / we.

Simple future, function
The simple future refers to a time later than now, and expresses facts or certainty. In this case there is no 'attitude'.

The simple future is used:

a. to predict a future event: It will rain tomorrow.

b. (with I/we) to express a spontaneous decision: I'll pay for the tickets by credit card.

c. to express willingness: I'll do the washing-up. He'll carry your bag for you.

d. (in the negative form) to express unwillingness: The baby won't eat his soup. I won't leave until I've seen the manager!

e. (with I in the interrogative form) to make an offer: Shall I open the window?

f. (with we in the interrogative form) to make a suggestion: Shall we go to the cinema tonight?

g. (with I in the interrogative form) to ask for advice or instructions: What shall I tell the boss about this money?

h. (with you) to give orders: You will do exactly as I say.

i. (with you) to give an invitation: Will you come to the dance with me?
Will you marry me?

NOTE: In modern English will is preferred to shall.

Shall is mainly used with I and we to make an offer or suggestion (see examples (e) and (f) above, or to ask for advice (example (g) above).
With the other persons (you, he, she, they) shall is only used in literary or poetic situations, e.g.

"With rings on her fingers and bells on her toes, She shall have music wherever she goes."