01In plain English
Layers work like clear sheets stacked on top of each other. Text, a photo, a shadow and a color adjustment can each sit on their own layer, so you can move, hide or change one without touching the rest.
02How it works
Imagine a stack of clear sheets of acetate on a desk. You draw a background on the bottom sheet, put a photo of a person on the next one, a drop shadow on the next and the headline on the top sheet. Looking down through the stack, you see one finished picture. The editor does the same on screen. Each layer can be moved, resized, hidden, made partly see-through or blended with the ones below, without disturbing the rest. Special adjustment layers apply color or brightness changes to everything beneath them. When you finish, you export a flat picture for the web or keep the layered file so you can come back and change the headline later.
03Why it matters when you are choosing
Almost all serious photo and design work depends on layers. Whether an editor can open and save layered files also decides whether you can swap work with clients who use Photoshop.
04What to check
Check whether the editor opens layered PSD files with their layers intact, and whether it supports adjustment layers and masks.
05Where you will meet it
06Common questions
What is a layered file?
It is an image file that keeps each part of the picture on its own layer, so you can edit the parts separately later. Photoshop's PSD is the best-known format. Flat formats such as JPEG and PNG merge everything into one picture, so edits to a single element are not possible afterward.
Can other editors open Photoshop layers?
Many can, with varying accuracy. Some keep every layer, mask and adjustment, while others merge effects or lose features such as smart objects and special blending. If you swap files with clients, test a real PSD in the editor first.
Do I need layers for simple edits?
No. Cropping, resizing or fixing the color of one photo works without layers. They matter once you combine several elements, such as text over a photo, or want to keep the option to change something later without starting from scratch.