Symantec Corporation (commonly known as Symantec) is an American technology company headquartered in Mountain View, California, United States. The company produces software for security, storage, backup and availability - and offers professional services to support its software. Netcraft]asseses Symantec (including subsidiaries) as the most-used certification authority. Symantec is a Fortune 500 company and a member of the S&P 500 stock-market index.