The dock can take up a good deal of screen space. You can set the dock to autohide if you want to reclaim this area.
Sometimes I am just dying for more room on my screen. Hiding the dock will create more room. This really reminds me of auto-hiding the taskbar on a windows machine.
The keyboard shortcut to hide the dock is CMD+option+D
You can also do this from the Apple menu…
1. Click the Apple menu in the upper left hand corner of the screen
2. Select Dock
3. Click Turn Hiding On