To toggle layer visibility, open the Layers tab and do one of the following:

To show or hide a layer, click the box to the left of the layer's name to toggle its visibility. A layer with check in the box is visible and a layer with an empty box is hidden.

To show or hide a parent layer and all its child layers at the same time, CTRL-click the parent layer and select Show Layer. This toggles the show/hide setting of both the parent layer and all child layers.

To show only one layer, CTRL-click the layer name and select Isolate. The selected layer and its children will be shown and all other layers will be hidden.