Before and after images of an actions that is saved in the Photoshop-Preset- Photoshop Actions folder. The above example is represents a change form a full colour RGB image into a Duotone image. This action can be saved and used on any photograph to obtain the exact same changes to the image.
The changes that you make on the photograph are global changes meaning that the changes that you make on the image will affect the entire image. Local changes that are unique to each image must be made after all the global changes are made.