An 'iframe' is an HTML element that creates an "inline frame" within a document, which allows displaying a separate document in the same page.
An <iframe></iframe> element allows the placement of an inline frame within an HTML document, which allows the display of another, separate document. Any content between the start and close tag of the <iframe> element is ignored.
First introduced by Microsoft Internet Explorer in 1997, standardized in HTML 4.0 Transitional, and allowed in HTML 5. [source]
An inline frame can be the "target" frame for links defined by other elements.
For more information, see MDN: <iframe> element and the W3C specification.
