Why doesn't CORS to websites work from a browser?

Question

JavaScript

Why does CORS not work from the browser and writes the error "Failed to load https://yandex.ru/: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. "
And if you make a request from a local server, everything is fine?

Answer 1

obviously they have registered the localhost in the headers, but the site from which you are trying to make a request is not