How do I hide the .htm file extension in the website URL?

i am trying to create a website with different pages and each page is a separate file, but i want to remove the file extensions from the URL

for example the URL looks like this:

https://website.com/contactus.htm

i want it to look like this instead:

https://website.com/contactus

i can't really find a proper solution to this and it's really confusing for me

does anybody have a solution?