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The Component Object Model (COM) is a software architecture that allows applications to be built from binary software components. COM is the underlying architecture that forms the foundation for higher-level software services, like those provided by OLE. OLE services span various aspects of commonly needed system functionality, including compound documents, custom controls, interapplication scripting, data transfer, and other software interactions." (Microsoft)  "ActiveX controls are among the many types of components that use COM technologies to provide interoperability with other types of COM components and services. ActiveX controls are the third version of OLE controls (OCX), providing a number of enhancements specifically designed to facilitate distribution of components over high-latency networks and to provide integration of controls into Web browsers." (Microsoft)  "The Distributed Component Object Model (DCOM) is a protocol that enables software components to communicate directly over a network in a reliable, secure, and efficient manner. Previously called "Network OLE," DCOM is designed for use across multiple network transports, including Internet protocols such as HTTP." (Microsoft)  "What, exactly, is COM+? COM+ is many things, but the basic answer is quite simple. COM+ is the merging of the COM and MTS programming models with the addition of several new features. COM was created long ago as a workstation-level component technology; with the release of Distributed COM (DCOM) in Windows NT 4.0, the technology was expanded to support distributed applications via remote component instantiation and method invocations. MTS followed. It was designed to provide server-side component services and to fix some of DCOM's deficiencies, e.g., how it handles security issues, and the complete lack of a component management and configuration environment. COM+ now comes along to unify COM, DCOM, and MTS into a coherent, enterprise-worthy component technology." (Visual C++ Developers Journal)  "Microsoft Transaction Server (MTS) combines the features of a TP monitor and an object request broker into an easy-to-use package. Developers use MTS to deploy scalable server applications built from ActiveX components, focusing on solving business problems instead of on the programming application infrastructure. MTS delivers the "plumbing" - including transactions, scalability services, connection management, and point-and-click administration - providing developers with the easiest way to build and deploy scalable server applications for business and the Internet." (Microsoft)  "Message Queuing (MSMQ), part of Windows NT Server, is communications technology that enables applications on different systems to communicate with each other, even if systems and networks occasionally fail. MSMQ does this by enabling applications to communicate with each other through messages. MSMQ guarantees delivery of messages even despite network and application failures." (Microsoft)