For example, perhaps you've dragged some folders to your Dock so that you can easily drop items into them, but you don't want to have to keep hovering your mouse over their generic blue icons to identify which is which.
To customize a file or folder icon, simply follow the steps below. You can use your own pictures as icons. Alternatively, there are a wealth of icon libraries hosted online, so you could try a web search for free icon pack downloads for Mac.
Note: If you find icons online in the .icns format, you can drag these icon types directly onto the icon in a file or folder's Info panel, thereby skipping the Preview steps described below.
- Double-click the picture or icon you want to use to open it in your Mac's built-in Preview app.
- Choose Edit -> Select All in Preview's menu bar, or use the keyboard shortcut Command-A.
- Choose Edit -> Copy in Preview's menu bar, or use the keyboard shortcut Command-C.
- Next, right-click (or Ctrl-click) the file or folder whose icon you want to change and select Get Info from the contextual menu.
- Click the icon in the top left of the Info panel to select it.
- Choose Edit -> Paste from the menu bar, or use the keyboard shortcut Command-V.
- Click the red traffic light to close the Info panel, and you're done.