The ACR interface
Open a Raw file in Photoshop CC and it will automatically launch Adobe Camera Raw in its own plug-in window (see below). The first thing to do is correct any lens distortions, such as barrel distortion from wide-angle lenses or pincushion distortion from using a telephoto optic. You’ll also want to fix any vignetting in the corners and chromatic aberration, where bright purple or green colours appear in areas of strong contrast. It’s near-impossible for a lens to not have any chromatic aberration, though premium lenses do a better job at mitigating this. The last of the initial tweaks is to apply a crop, as there’s little point working on areas that will be cropped out.