Understanding Layers
A layer is always transparent until you put something on it. Without layers everything was like one flat image and was akin to making a hole if you were to cut and move an object with a pair of scissors.
Before Photoshop, making any kind of change to a design was a major task. But with layers Tina can make any changes such as increase the size of the font on the heading with just a couple of clicks.
What are these layers?
Layers in Photoshop are like many photos, where each photo is mounted on a sheet of glass. As you move these photographs some of these become visible through or around other photos above it, while some photos are still obscured. Layers are transparent until you put something on it. Each layer remains transparent where no image data appear and other layers will show through.
The order of the thumbnails on the layers palette represents the order that the layers appear in the layer stack. You can change the order of the layers by moving a thumbnail image on the palette. The layers name appears next to a thumbnail.