Layers are the building blocks for creating designs in Sketch.
In other design tools, where the distinction between layers and objects is sometimes blurred, each object in Sketch is always on its own layer. We’ll be using the terms object and layer interchangeably throughout our documentation for that reason.
Groups and Artboards are used in Sketch to keep your content organized and they are also treated as layers in their own right. To add new layers to your document, click the Insert pop-up menu in the toolbar or menu and choose your layer type.