Ernst & Young Global Limited, commonly known as Ernst & Young or simply EY, is a multinational professional services network with headquarters in London, England. EY is one of the largest professional services networks in the world.

Along with Deloitte, KPMG and PricewaterhouseCoopers, it is considered one of the Big Four accounting firms. It primarily provides assurance (which includes financial audit), tax, consulting and advisory services to its clients.

EY operates as a network of member firms which are structured as separate legal entities in a partnership, which has close to 300,000 employees in over 700 offices in more than 150 countries around the world.