Sir Martin Sorrell founded WPP in the mid 1980s and is now a FTSE 100 giant with a value approaching £8bn. It has over 100,000 employees providing £30bn worth of services to clients in more than 100 countries.
An internet thought leader with a background in journalism, he was one of the original founders of Wired magazine and is a visiting professor at the University of California, Berkeley.
Matt left his role as director of strategy and digital at leading newspaper group Trinity Mirror to become Country Director for Google UK, where his work gives him deep insight into the needs of Google's largest clients.
Nick Hynes is a pioneer in search marketing. In April 2000, he led the European launch of Overture. Since May 2004, Nick has been CEO of the IMW Group, which includes The Search Works, Europe's largest agency dedicated to search marketing services.
Profile: Until July 2007, Stephen Taylor led the 'Audience Group' for Yahoo! Europe, giving him responsibility for all of the internet giant's European consumer businesses, including search, social media and the price comparison site, Kelkoo.
Our search podcasts accompany the White Box World feature and include contributions from one of the world's leading marketing gurus, Sir Martin Sorrell, and a pioneer of internet thought leadership, John Battelle.
In 2004, Richard became chairman of MySpace. During the next eighteen months, he led its transformation from a little-known site to one of the most-visited places on the web, increasing its value from $70m to $650m. Find out more about Richard Rosenblatt
As the vice president of research for Hitwise UK, Heather Hopkins analyses trends in traffic over the internet and works with the company's clients to help them grow their businesses online.
As a pure online player, Yahoo! increasingly finds itself competing for audiences - and therefore advertisers - with traditional media players who are rapidly expanding their presence on the web.
Peter de Monnink has a clear view of the forces shaping the online migration of brands - and a strong belief that the days of the print publication are far from numbered.
In 2005, Jeff Henry became head of the Consumer Division, where he is responsible for delivering ITV content through a range of new platforms.