Asking for a page
When you open a webpage, your browser sends an HTTP request. The website’s server sends an HTTP response, such as the page or an error. Apps use the same exchange to call an API.
HTTPS protects that exchange as it travels across the network. It encrypts the messages, and your browser checks a certificate to make sure the server matches the address you opened.
What HTTPS tells you
HTTPS protects the connection to an address; it does not prove the website is honest or its content is safe. A scam site can also use HTTPS.