You can control the transparency for selected objects, or for all objects on a layer. You can also specify a default transparency value for new hatch and fill objects.
Transparency effects can enhance drawings. For example, images of people placed in a building or operating machinery can be made transparent to de-emphasize them. Transparency can also be used to reduce the visibility of objects and layers that are intended for reference only.
In AutoCAD-based products that support 3D, solid and surface models have an X-ray visual style that applies a specified opacity level. The effects of opacity and transparency combine together.