Next to the Bridge button is the palette well. This is a space where you can keep palettes that you don't use as frequently or don't want occupying your workspace. It keeps them easily accessible, but hidden from view until you need them.
In the default workspace, you should have title tabs for the Brushes, Tool Presets, and Layer Comps palettes in the palette well. You can drag other palettes to this area and they will remain hidden there until you click on the palette tab to reveal it. When you need access to one of these palettes, just click on the title tab, and the full palette will expand below its tab.
Tip: If you cannot see the palette well on the options bar, you will need to adjust your screen resolution to at least 1024x768 pixels.
