You use Photoshop layers to perform tasks such as compositing multiple images, adding text to an image, or adding vector graphic shapes. You can apply a Photoshop layer style to add a special effect such as a drop shadow or a glow.
Photoshop CC (2014 release) lets you work better than ever before with Smart Objects. For instance, you can now package the linked smart objects in a Photoshop document with minimal effort. Read on for details.