Will

Nonetheless, perhaps as an extension of its temporal meaning, will is sometimes used with a modal sense conveyingon the part of the speaker (in addition to certainty that the intent will be carried out):

* "You will leave now."
* "I will find a way."

It bears note that English offers other ways to express the future tense — "It's happening tomorrow", "It shall happen tomorrow", "It's going to happen tomorrow" — and that some of these can also be used with modal meaning to convey intent.

Where a main clause uses the future tense with will, adverb clauses modifying it generally use a form of the present tense:

* "I'll let you know when I've done it." (not "when I'll have done it.")
* "I'll go if I wake up in time." (not "if I'll wake up in time.")

Nonetheless, there are certain cases where a protasis (if clause) can use will. This is especially common in expressing agreements:

* "I'll go if you go" or "I'll go if you'll go."
* "I'll do it if he promises to behave" or "I'll do it if he'll promise to behave."

Will will also sometimes be used with an aspectual meaning, indicating that something is commonly the case:

* (The above sentence is an example of this.)
* "Boys will be boys."

Or, similarly, that something is likely the case, because it matches a common case, as in the sentence, "I suppose you'll be hungry, after all that running you did?"; this use, however, is no longer common in most dialects.

Finally, there are some common expressions that use the word will: "I'll say"; "I'll bet" or "I'll wager."

The auxiliary verb will originally derived from a main (non-auxiliary) verb meaning to want. This other meaning survived a long time, especially the form of to will it, and is still widely understood today; nonetheless, its use today would likely constitute an archaism.