Adobe's Illustrator is a graphics program that was initially created for Mac computers in 1986. It is now available on both Windows and Mac Operating Systems (OS). While it has many similarities to Photoshop, Adobe's popular photo editing software, Illustrator is geared toward typography and logo graphic creation. Since 2003, it has allowed users to create 3D images, text and graphics. The cornerstone function of Adobe Illustrator is the concept of "layers."
When creating complex artwork, it’s a challenge to keep track of all the items in your document window. Small items get hidden under larger items, and selecting artwork becomes difficult. Layers provide a way to manage all the items that make up your artwork. Think of layers as clear folders that contain artwork. If you reshuffle the folders, you change the stacking order of the items in your artwork. You can move items between folders and create subfolders within folders.
Visibility Indicates whether items in the layers are visible or hidden (blank space), or whether they are template layers or outline layers.
Edit column Indicates whether items are locked or unlocked. The lock icon indicates that the item is locked and cannot be edited; a blank space indicates that the item is unlocked and can be edited.
Target column Indicates whether items are targeted for application of effects and edit attributes in the Appearance panel. When the target button appears as a double ring icon (either or ), the item is targeted; a single ring icon indicates that the item is not targeted.
Selection column Indicates whether items are selected. A color box appears when an item is selected. If an item, such as a layer or group, contains some objects that are selected and other objects that are unselected, a smaller selection color box appears next to the parent item. If all of the objects within the parent item are selected, the selection color boxes are the same size as the marks that appear next to selected objects.You can use the Layers panel to display some items as outlines and other items as they will appear in the final artwork. You also can dim linked images and bitmap objects to make it easier to edit artwork on top of the image. This is especially useful when tracing a bitmap image.