A VSDM file is a drawing created by Microsoft Visio, a diagramming and vector graphics application. It's similar to a VSDX file, but it contains macros. Macros are small programs that automate tasks within Visio, allowing users to create custom solutions and enhance the functionality of their diagrams. Because VSDM files can contain executable code, they pose a security risk if opened from untrusted sources. Visio uses VSDM to store a variety of diagrams, including flowcharts, network diagrams, organizational charts, floor plans, and more. The macro functionality allows for dynamic diagrams that can respond to user input or data changes. When opening a VSDM file, Visio will typically prompt the user to enable or disable macros, providing a warning about potential security risks. Disabling macros will prevent the code from running, but may also limit the functionality of the diagram.