Show (and Hide) Hidden Files & Folders in Finder

1. Go to the Applications folder.
2. Open the Utilities folder.
3. Open Terminal.
4. Enter the following commands, pressing Enter after each line:
   defaults write com.apple.finder AppleShowAllFiles TRUE
killall Finder
5. Press cmd + Q to quit Terminal.

To hide the files and folders again, change the word TRUE to FALSE in Step 4.