How Stripe keeps your card details secret

So how can it be that when you make a payment on our website, the URL (the webpage address) doesn't change but all of your card information is only seen by Stripe?

The URL is still on the Wise Owl site, but we never see any of your card details.

The answer starts with the header of the webpage: 

The page loads a library of JavaScript code from the Stripe website.

If you look at the HTML for the page itself, you'll just see a place-holder for the card number, etc:

Stripe fill this element with their own separate IFrame tag in HTML.

In the website, a JavaScript call then fills this card element with Stripe's HTML:

The IFrame from Stripe is injected into the appropriate element.

When you submit a payment, the page calls a Stripe routine to process it.