One of the most common tasks in Photoshop is making adjustments to images to fix tone and color.
Click on the icon to add an adjustment layer to your image.
The adjustments are grouped into three categories:
Tonal controls. Use these controls to adjust Brightness/ Contrast, Levels, Curves, and Exposure.
Color controls. Use these controls to adjust Vibrance, Hue/Saturation, Color Balance, Black & White conversion, etc.
Creative/Advanced controls. These controls are special adjustments and include Invert, Posterize, Threshold, Gradient Map, and Selective Color.
Adjustments appear on their own layer and offer nondestructive editing of your photos.
A Properties Panel will appear allowing you to modify the adjustment.
Adjustment layers (and optionally all layers) can have a Mask applied to control the visibility of the layer.
Masks are a useful way to erase parts of a layer non-destructively.
They can also be used to isolate an adjustment to only parts of an image.
Use the buttons across the top to switch between both the mask and adjustment layers properties.
Any Adjustment Layer will affect ALL Layers that are below it in the layer's panel.
In order to apply an adjustment to just ONE layer, you need to create a Layer Clipping Mask.
A Clipping Mask will tie the effect to the layer underneath it.
To apply a Clipping Mask, position the adjustment above the layer you want to clip to and go Layer > Create Clipping Mask, Right-Click on the Layer and select Create Clipping Mask or click on the Clipping Mask icon.