International Business Machines Corporation, abbreviated IBM, is a multinational computer technology and IT consulting corporation . The company is one of the few information technology companies with a continuous history dating back to the 19th century. IBM manufactures and sells computer hardware and software (with a focus on the latter), and offers infrastructure services, hosting services, and consulting services in areas ranging from mainframe computers to nanotechnology.

http://www.ibm.com

Microsoft Corporation is a multinational computer technology corporation that develops, manufactures, licenses, and supports a wide range of software products for computing devices.Microsoft most profitable products are the Microsoft Windows operating system and the Microsoft Office suite of productivity software.

http://www.microsoft.com

Oracle Corporation specializes in developing and marketing enterprise software products.The corporation has arguably become best-known due to association with its flagship product, the Oracle database. The company also builds tools for database development, middle-tier software, enterprise resource planning software (ERP), customer relationship management software (CRM) and supply chain management (SCM) software.

http://www.oracle.com