This is a follow up to the post of 9th January about automatically hiding and showing the menu bar, you can also automatically hide and show the dock, I find this really helpful while playing games in windowed mode.
Select System Preferences (img.1).
Choose the Dock icon in the top row of the window (img.2).
Now tick the, Automatically hide and show the Dock, checkbox (img.3)
When you tick this box, the dock will reappear as you move your cursor towards the bottom of the screen, allowing you to get at all your dock actions while keeping your screen uncluttered.