Ernst & Young Global Limited, trade name EY, is a British multinational professional services partnership based in London, England. EY is one of the largest professional services networks in the world. Along with Deloitte, KPMG and PwC, it is considered one of the Big Four accounting firms. It primarily provides assurance, tax, information technology services (including managed services in areas like Cybersecurity, Cloud, Digital Transformation and AI), consulting, and advisory services to its clients.
https://en.wikipedia.org/wiki/Ernst_%26_Young