Photoshop editing is mainly done using these 2 components extensively. The filters and the layers. Layers are those which are used in creating images, text, brushesstrikes., patterns, colours-background and filters application.

Layer as the name says, works on asingle part, without causing any harm or damage to the whole project when a change is made.  This is very helpful when you are working on anindividual part in a project,or asingle element in a project that needs editing, so that the rest of them aren't disturbed.

They are the most frustrating part to learn, but once you do, you will be glad and happy that you did know it well!

To have a better hand at layers, its always suggested that you save and name themseparately while working on a large project.