How does LESS work on the client side, why is a server required?

Question

Less

Some time ago I was building a site locally, opening html in a browser stupidly from a folder. At the same time, less.js refused to work. I fought for a long time until I asked LESS does not work in the browser. What's wrong?
However, I did not understand, and no one explained why exactly a server is needed. Does less.js work through an http request and itself re-pull the less file from the server? Or how?

Answer 1

I may not have read the question correctly, but I always work with loess locally using less. Js from the site, everything connects correctly and works.
Maybe I misunderstood the question