WPP plc is a multinational communications, advertising, public relations, technology, and commerce holding company founded in 1971 and headquartered in London, England. It is considered the world's largest advertising company.
WPP has approximately 130,000 employees throughout its portfolio of businesses across more than 100 countries, as of 2018.
WPP's notable advertising agency company holdings include Grey, Ogilvy, VMLY&R, and Wunderman Thompson. WPP's digital company holdings include AKQA. WPP's public relations and public affairs company holdings include Hill+Knowlton Strategies, BCW (Burson Cohn & Wolfe), and Ogilvy.
WPP's media investment management company holdings include GroupM, Mindshare, Wavemaker and Essence. WPP's research insight and consulting companies include Kantar. Hogarth Worldwide is a WPP-owned production company.
WPP-owned brand consultancies include Superunion (a combination of Brand Union, Lambie-Nairn, and three other brand consulting businesses) and Landor.
According to en.wikipedia