What is an iframe in HTML?

An iframe, which stands for inline frame, is an HTML element used to embed another document within the current HTML document. This allows for the inclusion of content from other web pages, including text, images, videos, or even other websites, directly into a specified area of the current page. The iframe operates like a window to another document, allowing content to be displayed without navigating away from the original page.

The distinction of being "inline" means that the iframe can seamlessly coexist with other content on the page, appearing as part of the document's flow. This capability makes iframes particularly useful for embedding content such as interactive maps, media players, or entire web applications within a webpage, thereby enhancing user experience and engagement.

While other options refer to different HTML functionalities or elements, they do not encapsulate the purpose and definition of an iframe effectively. For example, pop-ups involve JavaScript or other methods for displaying content in new windows rather than within the flow of the document, and embedding images typically utilizes the <img> tag, while deprecated tags for videos might refer to older practices that are no longer recommended in modern HTML standards.