Shadow Creation Services is basically being created by adding a custom shadow after separating the object and the background. The background may be entirely deleted or somehow modified. Shadow is made when an object blocks light. The object must be opaque or translucent to make a shadow. A transparent object will not make any shadow, as the light will pass straight through it.
When it comes to professional photography, shadows, being the darkest part of an object (and the opposite to the highlights) are one of the most preferred tools to apply to images. In fact, shadows in photography can be divided into two main categories: drop (box) and cast (natural) shadows. While the first category is mostly decorative and somehow “illusional”, the second one is, apparently, used to outline deeper, more realistic images.