When we want to express ability, possibility, willingness, certainty, necessity, or obligation, we can use modal verbs.
We use modal verbs “will” and “would” to emphasize habits and behavior that are characteristic of someone. We use “will” for the present and “would” for the past.
Tom and Mary always spend their holidays at their favorite inn at the seaside. They'll get up late, have breakfast and go to the beach afterwards.
When Tom and Mary were kids, they used to spend their holidays at the seaside. They'd get up late and have breakfast, then they'd go to the beach.
Also, “will” and “would” tell us about things that were or are true.
Hot weather will kill the virus.
During WWII, people would eat the things that we won’t eat now.
We can also use “will” to draw conclusions or state assumptions about true things.
No doubt you will have known the truth by now.
When we want to talk about willingness or refusal to do something, we can use “will”.
The deputy says that she will dissent if no solution is to be found.
We can use “would” when we want to talk about willingness in the future or in conditionals, also when we are willing but unable to do something.
The deputy would be happy to be at the meeting if it were not for the circumstances beyond his control.
When we are talking about a particular occasion, we can’t use “will” or “would”.
Each time I gave her a call, she would answer me.
Yesterday I gave her a call and she answered me.
If we want to say that we suppose that a past situation happened, we can use “will have” + past participle.
It's seven o’clock. Tom will have finished the task by now.
To talk about the things that happened repeatedly in the past and aren't happening any longer, we can use “would” or “used to” + infinitive. But we can’t use “would” if the time reference is clear.
Kate used to have blond hair.
Every day, Rachel would take the number 8 bus to school.
When the past states have changed, we use “used to”, not “would”.
They used to be isolated because the transport service was so poor.
Another structure is “to be used to sth / doing sth”, which means to be accustomed to something or doing something. It can be followed by a subject or a gerund.
Today I have been living in the UAE for five years. I am used to hot weather.
I am used to hard work or I am used to working hard.