Subtle Drop Shadows
This can be used to differentiate text from the background as a strategic graphic design element with a purpose. The basic solution is to make it easier to read by implementing more contrast.
Hard Edge Drop Shadow
Using a hard edge shadow behind the text can give off a retro vibe, especially if it's slightly separated from the text. It's an excellent way to draw more attention to particular words or images.
Long Drop Shadows
This is a very trendy design, and if used properly, can be a significant design element. It utilizes the flat icon and reflects a minimalist look. These long shadows provide movements to the icon and offer a unique and simple design element that doesn't cause too much distraction.