At any given moment while working with Photoshop, you have two colors available. Only two? Don't worrythat's really kind of misleading. Perhaps it's better to say that you have two colors
active : a foreground color and a background color. The
foreground color is the one you use to paint, to fill or stroke a selection. It's the color that's currently on your brush or pencil. (You'll learn about filling and stroking later when you read about paths.) The
background color is the color Photoshop uses when you erase or delete a selected area on the background layer. You might think of it as the color of the canvas under your painting.