Because you have a great amount of flexibility when working with layers. layers can be edited, added or deleted at any time also can be used for non desctructive corrections which means you are not working directly with pixels.
BY working a layers you are building up a picture or editing a picture where you work on its own "page" therefore each is independent and makes up the whole visual effect
by using layers you can manipulate same areas without effecting the master picture. It allows for easier changes and mapping
There are many resources and websites that offer information about Photoshop layers. Some of these websites that offer information are Adobe, Photoshop Essentials and Photoshop Cafe.
color layers is simply color layers
Open the Layers window.
Yes, .psd files maintain the layers you create in Photoshop so that the next time you open your .psd file in Photoshop you can continue to work directly onto the layers.
One layer.
To store image parts.
To select all layers in photoshop for a PC open up your layers window (It is under window - layers), hold down the shift key and click on each layer that you want to group together or edit.
Flattening layers just merges all layers down into one. It reduces file size, but once the image is saved and Photoshop is closed, you will no longer be able to undo the change and edit those layers separately.
I opened a new project in Photoshop Elements 6 and began adding layers. I'm at over 360 and it hasn't stopped yet :D My guess is, it will add as many layers as your computer can handle without crashing.
Don't know how it actually does it, but you can only save layered images in format that supports them. ie: photoshop native files .PSD or layered TIFFs. Jpegs can not be saved with layers.
The Move Tool allows you to rearrange layers in Photoshop by dragging and dropping.
layers are separate images stacked one above another, layers can have transparent areas so you can see content below