Masking in Adobe Photoshop is this great technique to reveal certain parts of your image or artwork while concealing some parts. The dictionary meaning of masking is to conceal something from view. The same meaning is implied in Photoshop as well. Masking in Photoshop makes use of two colors; black and white. The concept behind Masking is that, if you paint black over an image it is concealed and if you paint white over it it is revealed. While masking the colors are painted with the Brush tool. The shortcut for Brush tool in Photoshop is the letter ‘B’ in the keyboard.
Now you may be wondering why not simply use the Eraser tool instead of Masking. The disadvantage with Eraser tool is that once you erase portions of your image, you cannot get the original asset in future. But, if you use Masking in Photoshop, you have an added advantage that your original file is always preserved. In case you need to get your image file back in future all you need to do is paint white over your image or delete the mask itself.
The steps below are described referencing Adobe Photoshop CC.
Steps involved in Masking in Photoshop:
1. Select the layer you want to create a mask on.
2. Click on Layer -> Layer Mask -> Reveal All.
3. You will see a small white box appears next to your layer. This is the box you will be painting in the blacks and whites with your Brush tool.
4. Click on that small white box and select Brush tool from the toolbar. (SHORTCUT: ‘B’ on the keyboard)
5. Select the black color from color palette and start painting black. You will see the area where you painted black is concealed.
6. Select white color now and paint over those concealed areas. Your image is restored to how it was before.
To delete a Layer Mask in Photoshop:
1. Right click on the small white box that appeared next to your layer.
2. Click on Delete Layer Mask.
3. If prompted by a dialog box, click on Delete.