Viewport

Related: scrolling

[Viewport] refers to the part of the document being viewed in the browser window (or on-screen, if the document is being viewed on a mobile browser or a desktop browser in full-screen mode). Content outside the viewport is not visible onscreen until scrolled into view. [MDN]

Viewport Meta Tag

• developer.mozilla.org/en-US/docs/Web/HTML/Viewport_meta_tag
• developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/meta/name#standard_metadata_names_defined_in_other_specifications

Especially on mobile devices, some components of browser UIs can cover/change the viewport. For example, the on-screen keyboard or a search bar. The interactive-widget property of the viewport meta tag can be used to specify how exactly the viewport changes in these situations. [MDN, spec, chrome-dev]. This feature is not available in Safari [WebKit/standards-positions#65].