You can use the Layer Properties Manager to control the visibility of objects and to assign default properties to objects on each layer.
You can make the objects on a layer invisible either by turning the layer off or by freezing it. Turning off or freezing layers is useful if you need an unobstructed view when working in detail on a layer or set of layers, or if you don't want to plot details such as reference lines. Whether you choose to freeze layers or turn them off depends on how you work and on the size of your drawing.
You can lock a layer to prevent objects on that layer from being accidentally selected and modified. The LAYLOCKFADECTL system variable controls the amount of fading assigned to a locked layer. Fading the objects on locked layers contrasts them with objects on unlocked layers.
Each layer has associated properties such as color, linetype, and transparency that are assumed by all objects on that layer when their object properties are set to ByLayer instead of a specific value.
Using the Layer Manager, some layer properties can be changed using overrides within a layout viewport. Using layer property overrides is an efficient way to display objects with different property settings for color, linetype, lineweight, transparency, and plot style. Layer property overrides are applied to the current layout viewport.
For example, if you want objects on the Electrical layer to display prominently in one of two layout viewports, you set a Color override on the Electrical layer for each of the two viewports. By setting the color red for one viewport and gray for the other, you easily accomplish this objective without changing the global color property assigned to the layer.