Why is it possible to press the footer only with this (height: 100vh;) parameter?

Question

css

I tried to push the footer to the bottom of the page using flex, nothing worked, I found a way that you just need to add "height: 100vh;" to body or another main container. I don’t quite understand what the value of 100hv means, I didn’t encounter this before, before it pressed even without these parameters, maybe it was because there was enough content on the page.

Answer 1

.footer {
position: absolute;
bottom: 0;
width: 100%
}
write it down and you will be happy