ISO/IEC 19775 Extensible 3D (X3D) defines a software system that integrates network-enabled 3D graphics and multimedia. Conceptually, each X3D application is a 3D time-based space that contains graphic and aural objects that can be dynamically modified through a variety of mechanisms. This part of ISO/IEC 19775 defines the architecture and base components of X3D.

The semantics of X3D describe an abstract functional behaviour of time-based, interactive 3D, multimedia information. This part of ISO/IEC 19775 does not define physical devices or any other implementation-dependent concepts (e.g., screen resolution and input devices). This part of ISO/IEC 19775 is intended for a wide variety of devices and applications, and provides wide latitude in interpretation and implementation of the functionality. For example, this part of ISO/IEC 19775 does not assume the existence of a mouse or 2D display device.

Each X3D application:

1. implicitly establishes a world coordinate space for all objects defined, as well as all objects included by the application,
2. explicitly defines and composes a set of 3D and multimedia objects,
3. can specify hyperlinks to other files and applications,
4. can define programmatic or data-driven object behaviours,
5. can connect to external modules or applications via programming and scripting languages,
6. explicitly declares its functional requirements by specifying a profile, and
7. can declare additional functional requirements by specifying components.