Actions capture all of the steps needed to transform a file and let you apply them with just one click. And with a single click, you can take the creative effect and workflow steps from another artist and add them to your own picture, creating everything from improved portraits to radically altered double-images. Photoshop actions can also be extremely useful timesavers when you find yourself performing the same steps on all of your image.
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100 Free Photoshop Actions (And How to Make Your Own)