When used on an anchor, this attribute signifies that the browser should download the resource the anchor points to rather than navigate to it.
Resource Hints: prerender
Gives a hint to the browser to render the specified page in the background, speeding up page load if the user navigates to it. This is indicated using `<link rel="prerender" href="(url)">`
Portals enable seamless navigation between sites or pages. A new page can be loaded as an inset using the `<portal>` element (similar to an iframe) which can then seamlessly transition to the new navigated state when "activated".
request api: `request()` constructor: cross-origin `referrer` stripped out and `navigate` mode converted to `same-origin` when constructor created from existing `request` object.
request api: `request()` constructor: `navigate` mode
headers http header: csp: content-security-policy: navigate-to