D avid Filo is an American billionaire and the co-founder of the internet portal and media company Yahoo!. While a PhD student in electrical engineering at Stanford University in 1994, he and his classmate Jerry Yang created a web directory called 'Jerry and David's Guide to the World Wide Web'. This hobby project, designed to help them keep track of their favorite websites, quickly grew in popularity and was renamed Yahoo!.

As the company's 'Chief Yahoo', Filo was the technical mastermind behind the scenes, developing the underlying software and infrastructure that powered one of the most popular websites of the early internet era. Yahoo! went public in a hugely successful IPO in 1996, making Filo and Yang young billionaires. While Yahoo has since been eclipsed by rivals like Google and Facebook and was largely acquired by Verizon, Filo has retained a significant stake in the remaining entity (now just called Yahoo) and remains on its board, making him one of the enduring billionaires of the first dot-com boom.