You link two or more layers together so you can apply transformations equally to each layer without having to merge them first. This gives you the flexibility to make later transformations independently. While Link Layers allows you to move, resize, rotate and flip layers in unison, it only applies to these types of transformations. You can’t apply a filter to several linked layers simultaneously. You either need to apply the filter to each layer independently or merge the layers first. It is easy to link layers once you know how, but because the buttons are unmarked initially, you can easily overlook them. If you’re familiar with linking layers in Adobe Photoshop, this technique will be a little alien, particularly as there is no option to have more than one group of linked layers at any time. In most cases, however, this shouldn’t be an issue unless you regularly work with documents with large numbers of layers. Using the option to link layers will give you the flexibility to apply transformations quickly and easily to multiple layers, without losing the option to apply changes to individual layers later on.