3D projections are visual representations that display three-dimensional objects on a two-dimensional surface, such as a screen or paper. They help viewers understand the depth and spatial relationships of objects, making them useful in fields like architecture, engineering, and gaming. Common techniques include perspective projection, where parallel lines converge at a vanishing point, and orthographic projection, which maintains the object's proportions without distortion. These projections can be created using various software tools and techniques, allowing designers to visualize their ideas more effectively. In addition, 3D modeling software often incorporates these projections to help users manipulate and view objects from different angles, enhancing the design process.