COM+ is a programming model based on Component Object Model (COM). COM+ does not replace the COM. In fact, COM+ technology uses the COM by extending its features to provide enterprise level services.

COM was the very first methodologies to facilitate object oriented software implementation. It is mainly used to encapsulate business task and logic into one business object, called COM component in the distributed environment which can be shared and accessed by different applications.

In the real world scenario, more than one COM component work altogether to achieve a high density task. To manage the integrity and security among different components, COM uses another service of Microsoft, called Microsoft Transaction Server (MTS).

In other words, COM+ is nothing but a combination of both COM and MTS. It means COM+ = COM + MTS. COM+ was first introduced in Microsoft Windows 2000 Server. COM+ also includes additional features like object pooling, load balancing, component queuing, etc. These services were being known as the COM+ Component Services. When multiple components are grouped together it is referred to as COM+ applications.