You can also select the layers or groups with keyboard keys. If you have 'layer edges' turned ON, then it is easy to see the content.
Here i have five layers in my layer palette (fig 1.0) and named them in alphabets for easy explanation.
(For the sake of this tutorial, pretend the 'Background' layer does not exist)
To select the layer on top of the current selection, Press Alt + ] (alt + right square bracket). If you want to select the bottom layer then press Alt + [ (alt + left square bracket).
If you keep pressing the keyboard key, the selection keeps moving in cycles
Easy way to remember the action is -
Right square bracket: Forward (top)
Left square bracket: Backward (bottom)
Once you reach the end of the layer and if you press the same key, it will cycle through. In the top image (fig 3.0) i have the layer 'A-head' is selected and if i press the alt + ] key, the bottom layer 'E-tail' will select.
Hidden layer cannot be selected. But you can select locked layers.
If you have a set of layers inside a group and if the group is closed, you can only able to select only the group. Moving the selection will not open the group.
Select multiple layers
You can also make Multiple selections by using alt + Shift + ] and alt + Shift + [
Once you have selected two or three layers above the current selection; pressing Alt + Shift + [ will continue the selection in reverse.
Notice the 2nd image (fig 6.0), once i pressed alt + Shift + [ it doesn't deselect the top layers, instead it is started selecting the bottom ones.
Like a normal selection, you cannot select if the layer is hidden.