Why can my site open both via http and https at the same time?

Question

HTML

I added a certificate to my site and everything is super, it works, but as it was said in the question, my site opens the same way without a certificate,
how can I make the site open only via https in any case, even if the user enters http?

Answer 1

Add a redirect from HTTP to HTTPS, for example, via .htaccess
Add an HSTS header.

Answer 2

To do this, you need to add an unconditional redirect to the web server config.