The Shadow Effect
You can add a Shadow effect to an object to create a drop shadow. You can also add an Inner Shadow effect.
The Appearance panel is used to add and adjust the effects.
1 - Visibility of an effect.
2 - Add a new effect.
3 - Open settings of an effect.
4 - Delete a selected effect.
5 - Click to adjust the color of an effect. This button opens the Color panel.
In order to add a shadow, click on the plus button in the Appearance panel. Select Shadow or Inner Shadow. Then click on the gear icon of the effect and set up its properties. You can also change the color of the shadow.
The Shadow effects create raster graphics. If you plan to export a high-resolution image, or, if the exported image might be enlarged in other software, make sure that your export settings are sufficient for that.