Drop shadow effect
Add a drop shadow around the objects visible on the layer.

Distance and Rotation set how far and in which direction the shadow is offset from the object, while Blur softens its edges. You can also change the Color of the shadow.
Enable Shadow only to hide the object itself and render only its shadow. This is handy to create a separate shadow (for example on the ground) by placing a copy of the object with this effect enabled.
Reference
All effects are listed in the effects reference page.