Ernst & Young (doing business as EY) is a multinational professional services firm headquartered in London, England, United Kingdom. EY is one of the largest professional services firms in the world and in the league of the "Big Four" accounting & consulting firms globally. The firm has recently diversified into digital advisory services as part of its multiyear expansion strategy to strengthen the portfolio of consulting services in the advanced technology areas. EY operates as a network of member firms which are separate legal entities in individual countries. It has 270,000 employees in over 700 offices around 150 countries in the world. It provides assurance (including financial audit), tax, consulting and advisory services to companies.