This guide shows you how to show/hide hidden files (and folders) in any version of Mac OS X.
Example: You’re looking for a file in Finder, but can’t find it. It’s most likely hidden.
Resolution: Go to Finder > Applications and start Terminal. To show/hide these files, use the following commands:
defaults write com.apple.finder AppleShowAllFiles TRUE
defaults write com.apple.finder AppleShowAllFiles FALSE
You can also download the following Automator script that does the above for you.