A clipping or layer mask is the use of masks, so that only certain parts of the image are displayed. For example, a form would be drawn into the base layer is known as a mask (the layer below right) after that all the layers and images would be located on these layers show only the parts of the image that fall within the scope of the mask and the parts of the images that are outside the mask, would be hidden this is known as the average rate.

Clipping masks can be used to produce very strong visual effects, techniques such as image mixing to stylization texts. Clipping masks can be used to make some bold statements. Mixed refers to the use of two source images that are blended into one. Stylized text using fonts and text boxes as a mask, so that the text is in the base layer and the images are placed over it. All images placed on it then take the form of the text at the base of the image. This can be improved by adding a different background than your average rate and by the use of alpha channels.
Clipping Mask vs. layer mask

Layer Mask is a masking 12:59 service, which applied a single mask means with a single layer. Although masks can be replicated to other layers, it effectively means that each layer has its own mask while a clipping mask has a one-to many masking style, which means that a single mask too many layers can be applied.

Thus, in one layer, each layer in the image mask has a separate mask is even though the result appears to be the same as that of a clipping mask, requires a layer mask to perform much more time and is also dense in terms of file size. can be applied in a clipping mask as a single mask on multiples layers, the process is much faster and reached the file size smaller than that of a layer mask.