http://www.associatescloud.com - Background Remove / Knockout is commonly used for taking out the product/object from its background for making product catalogs, inserting an object to a portion of a design. Background remove/Knockout sometimes refers to the concerned service like Clipping Path / Image Masking when asked an object (like hair, dag, translucent images like glasses, blaze, rousing etc.) to leave it on clear background or on a different background.
Background Knockout service is required to create transparency without losing the translucency, change / use a customized background, to put on a catalog / magazine