How to make pages not have extensions?

[lullabyflow]

Hi! I want to know how people can make it so that website pages do not have extensions.

I know that the first page will be index.html, but for links, I've seen pages that are like www.blah.com/blah/ rather than www.blah.com/blah.html, you know?

So far, what I have done is created a folder within my website and named it page and put an index.html in that folder, so my link would become www.blah.com/page/ and my code is <a href="page/index.html"> (because <a href="page"> just leads me to a link with everything in that folder including my .xmls and images and stuff)

However, that's all I can really do. If I wanted to go back to the homepage to just www.blah.com, I wouldn't know how, and I wouldn't know how to make it go to another folder's index.html unless I make another folder in that folder.

P.S, if it helps, I do not have a domain name yet so I can't just type it in. I am doing this as an assignment for school, so it's really just based on folders as of now.

Is there an alternative way?

Sorry if this was confusing! :( I am terrible at explaining
But thanks in advance :)