Поэтому я хотел разобраться понимает ли человек как происходит загрузка на сервер
When the user completes the form, and selects the SUBMIT element, the
browser should send the form data and the content of the selected
files. The encoding type application/x-www-form-urlencoded is
inefficient for sending large quantities of binary data or text
containing non-ASCII characters. Thus, a new media type,
multipart/form-data, is proposed as a way of efficiently sending the
values associated with a filled-out form from client to server.