Sometimes you need to view only one layer in PhotoShop, but hiding all the other layers one-by-one can be incredibly cumbersome. Luckily there is a shortcut for it. Hold down the OPTION key (ALT on Windows) and click the visibility icon (the eyeball) beside the layer. It will toggle the visibility of all other layers to hidden. OPTION + click it again to undo it and see everything again.
A word of warning. If you do this to hide all the other layers, and then click to individually change the visibility of a layer, then when you try to OPTION + click the visibility icon again to toggle all the layers back to visible it will no longer work. Photoshop will “forget” what layers it hid.