Drop Shadow......................

Drop shadow is a graphic effect that creates the illusion of a light source shining on an object from above so that a shadow appears to be shed behind the object. It gives an image depth by creating shading offset behind or beneath an image which gives the illusion of shadows or mock shadow from lighting and gives a 3D effect to the object. White or very light background is more preferable for the best output of drop shadows. Putting a gray or black area underneath and offset from the object will give a very arty look. A drop shadow gives a floating dimensional effect.

The Drop Shadow service need for In the pitch of web media, advertisement media, online marketing, product photography and promotion and any other visual presentation

Thanks for your short description about drop shadow....but what is your question?

Drop Shadow is also a creative works to make illusion of object . Actually you told enough . So thank you

The traditional use for a drop shadow is to simulate 3D depth in a 2D image. This is done by creating an offset shadow behind an object to indicate that the object is hovering above the background in 3D space.

Below you will see an example of how a drop shadow can indicate how big the light source is and where it is coming from, as well as how far away an object is from the background. By changing only the settings of the shadow, you can dramatically change the look of an image

The Layer Styles Drop Shadow Dialog Box

Yes,

Drop shadow is used to improve quality of picture attraction by giving same shadows under the image. And I think you have already give proper idea about drop shadow.