Abbreviation of COM Component Object Model
, it was introduced by microsoft initially to pave a way for inter process communications. In order to make use of a COM component in an application first it has to be registered to the registry, which will also create a class id for it in the registry.
When you try using a COM component in your application it will create a COM callable wrapper which is often termed as the COM interop.
After COM microsoft came up with COM+, the major problem which was raised by the COM usage was "The Dll Hell", which was not allowing multiple versions of the same COM component to be registered until the older version is deleted. The .NET framework was introduced by Microsoft which made use of the GAC instaed of registry there by extending the support for multiple versions of a library.
In order to register a COM component in your machine, you can make use of the Regsvr32 command. Below is the syntax of it.
regsvr32 -i <dll name with path>
regsvr32 -u <dll name with path>