Will (/wɪl/) is an English full modal verb that is used to express certainty. "The sun will rise tomorrow". There is also a lemma-distinct regular lexical verb "to will", which has a different meaning and different grammar.
The preterite of will is would.
As it is a full modal verb it lacks a past participle, present participle and infinitive. It's possible to create an artificial infinitive by circumlocution by using "to be going to", or for would "using to".
Will has a final /l/ sound which may be dark before a consonant sound or at the end of an utterance or light before a vowel sound.
Won't often has the final /t/ reduced to a glottal stop; /wəʊnʔ/.