What is a Layer Group?
A layer group is like a folder of layers.
In layer-based applications such as image editors and video editors, a layer group is a virtual object similar to a layer, such that it appears in the layers list and has its own name, but that has a different purpose: instead of containing data to be applied to the canvas like a layer would, a layer group's purpose is simply to contain other layers.
In some applications, layer groups can contain other layer groups, creating a hierarchy of layers.
In applications that support layer blending modes, layer groups can have two different modes of operation indicated by a special blending mode that only layer groups can have. When a layer group's blend mode is "pass through," the purpose of the layer group is purely organizational and there is no difference to how layers are blended if we remove the group. When the blending mode is anything else, including "normal," the layers within the group are blended as if they were in an empty canvas, and the layer group works as if it was a single layer whose contents were equivalent to the result.