What is the main characteristic of projections that attempt to preserve all properties without distortion?

Projections that seek to preserve all properties without distortion are fundamentally constrained by the nature of cartography. According to the concepts of map projections in GIS, it is impossible to create a single projection that maintains all spatial properties—such as area, shape, distance, and direction—accurately at the same time. This is due to the inherent challenge of representing the curved surface of the Earth on a flat plane, where some degree of distortion is inevitable for at least one property.

Although there are different types of projections designed to minimize distortion for specific properties (such as equal-area projections for area or conformal projections for shape), a projection that perfectly preserves all properties does not exist. This characteristic is one of the foundational principles in understanding how various projections serve different purposes based on the needs of a specific task or analysis in GIS.

The other options point to aspects of projections that do not apply universally; for instance, some projections do represent areas accurately but do not preserve shapes, while realistic 3D models serve different functions and typically do not apply to traditional flat projections. Online mapping also relies on specific projection types that prioritize usability over aesthetic realism, rather than aiming to preserve all properties without distortion.