If you like your dock icons to be organized, then this tip of for you. Make grouping of your dock items and separate them with padding spacers like this sample.

You have to go to the terminal to do this, so open Applications/Utilities/Terminal and enter the following commands.

defaults write com.apple.dock persistent-apps -array-add '{tile-data={}; tile-type="spacer-tile";}'

and then enter:

killall Dock

to see the newly organized dock. Type exit to quit the Terminal.

You can then move the spacers to any location on the dock just as you can with a application icon. The spacer can also be deleted by dragging the spacer off the dock as normal.