01In plain English
Layers work like clear sheets stacked on top of each other. Text, a photo, a shadow and a colour adjustment can each sit on their own layer, so you can move, hide or change one without touching the rest.
02Why 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.
03What to check
Ask the vendor
Check whether the editor opens layered PSD files with their layers intact, and whether it supports adjustment layers and masks.