What are Lightroom masking tools?
Masking tools let you apply an adjustment to one specific area of a photo, rather than the entire image. If you want to make the subject of your photo pop by increasing its saturation while leaving the background as is, put a mask over your subject and adjust the saturation on the masked area.
Fine-tune your mask overlays.
Any edits you make to masked areas are nondestructive, meaning you can go back and adjust them later. You can also adjust the shape of your mask and what’s included in it with easy-to-use tools.