An IFrame (Inline Frame) is an HTML document embedded inside another HTML document on a website. The IFrame HTML element is often used to insert content from another source, such as an advertisement, into a Web page. Although an IFrame behaves like an inline image, it can be configured with its own scrollbar independent of the surrounding page's scrollbar.
In 2008, hackers seeded Internet search results with malicious IFrame code, leading to IFrame overlay attacks on many prominent websites, including those for USA Today and ABC News. The attackers inserted IFrame code into the saved search results of legitimate websites. When a visitor clicked on a link from the compromised search tool, he would be redirected to a malicious website by the IFrame code. The unsuspecting user's computer would then be vulnerable to the automatic download of malware.