Layers panel
View > Panel > Layers
Alt+6
Shows a list of the layers in the current document. If you click a layer in the list, it will be selected in the document window. Double-click a layer in the list to open the Layer Properties dialog box for the layer.
Layers snap to each other
Checking this option makes layers attract each other when you move them.
Columns
ID
Shows the name of each layer.
Z
Shows the Z-index of each layer. The z-index of a layer determines whether it is in front of or behind other overlapping layers. To bring a layer to the front, assign a higher z-index for it. To send it behind others, assign it a lower z-index.
Visibility
Shows the visibility setting of each layer. If the visibility of a layer is set to Default, nothing appears in the Visibility column for the layer.