This is a layer containing an image adjustment or effect instead of image content. Like a red Cellophane overlay on a print, an adjustment layer will alter the appearance of layers below it, but not actually alter their content, making adjustment layers a cornerstone of reversible, ‘non-destructive’ editing. The adjustment can be altered, hidden or removed at any point. When you add an adjustment layer, a mask is also automatically created, so that the effect can be applied to a lesser extent (or not at all) in particular areas of the image. The Adjustment Layers in Photoshop are a group of a super useful, non-destructive image editing tools that add color and tonal adjustments to your image without permanently changing its pixels. With the adjustment layers, you can edit and discard your adjustments or restore your original image at any time.