WPP is a British multinational advertising and public relations company and the world's largest advertising company.WPP plc owns a number of advertising, public relations, media, and market research networks, including Ogilvy, J. Walter Thompson, Young & Rubicam, Grey, IMRB, Millward Brown, Burson-Marsteller, Hill & Knowlton, TNS, GroupM, Kantar, and Cohn & Wolfe.