An IFrame (Inline Frame) is an HTML element that allows you to embed another HTML document within the current page. This means you can display content from another website or a different part of your own site without leaving the original page. IFrames are commonly used for displaying videos, maps, or advertisements. IFrames are defined using the `<iframe>` tag in HTML. You can specify attributes like width, height, and source URL to control how the embedded content appears. However, some websites may restrict their content from being displayed in IFrames for security reasons, using a technique called X-Frame-Options.