PALETTES in Illustrator tell you what is going on with specific parts of artwork you have created and help you to make changes to that artwork.
When you open Illustrator, you will see different sets of floating PALETTES in default groups.
To bring a PALETTE to the front of it’s group, click on the tab that shows the PALETTE'S name and the PALETTE you want will appear on top.
A check mark next to a PALETTE name means that a particular PALETTE is currently displayed on screen in the front of it’s group. To remove a PALETTE that is floating on your screen, scroll down to that PALETTE name and release your mouse and the PALETTE will disappear from your workspace.
Many of Illustrator’s PALETTES can be viewed by name, or from a minimal, compact, or expanded view. If the PALETTE tab has a double triangle to the left of the PALETTE name, click on it to see the different views of the PALETTE.