How to hide Dock on non-fullscreen desktop
You can hide/show the Dock by pressing optioncommandD which checks/un-checks the Automatically hide and show the Dock checkbox under System Preferences > Dock, and then application windows can occupy the space normally used by the Dock.

When hidden, you can have the Dock temporarily reappear by moving the mouse to the bottom of the screen (that's assuming you have it in its default location).