I have a question about Create a Form Element

<form action="/url-where-you-want-to-submit-form-data"></form>

Why would you allow to send a form anywhere? For example imagine a log in to free code camp when you don’t own the website?

you also need a back-end made to receive the data, otherwise the data are essentially lost

I’m confused by the question, the url-where-you-want-to-submit-form-data points to a script that processes the form data you’ve sent.

Whenever you fill out a form and submit, you send the form data to the owner of the website. Otherwise fCC wouldn’t know your email address, for example.