Extensions to 3ds Max are called plug-ins. A plug-in is implemented as a DLL. Much of the functionality of 3ds Max is provided as plug-ins. This section lists most of the over 50 different plug-in types that can be built using the 3ds Max SDK.
The source code of many of the 3ds Max plug-ins are provided as samples in the /samples folder of your 3ds Max SDK installation. In addition several tutorial samples, called how-to samples, are provided in the folder /howto and are intended primarily for illustrative and educational purposes.