Dock
From ICHKWiki
The dock is the almost transparent component at the bottom of the screen which shows the applications and minimised windows on your macbook screen. It makes it easier to chose an application on your Mac It also tells you what sort of application is running on your computer by marking it with a blue dot underneath. The size of the dock can be changed, by going to System Preferences, clicking on 'Dock' and then you can adjust the size according to your convenience.
You can even change the position of the dock on your screen. It can be placed at the bottom or side. If you chose to make the dock 'hide you the dock can also appear only when you hover your mouse over the bottom of the screen. To open an application just click on the icon.
Deleting an icon
If you want to delete one of the icons, you can easily drag it out of the dock and see it 'poof' away. If you wish to quit an icon to speed up your computer (An open application keeps the mac running slower) you can hover your mouse over the icon and right click (Control click) It will give you a few options, such as new window, options, hide and quit. You have to press quit to lose the blue dot.
