To display hidden files & folders

1. Open Terminal (from /Applications/Utilities)

2. Issue command

defaults write com.apple.finder AppleShowAllFiles -bool true

3. Kill the Finder to take effect by issuing the command

killall Finder

To hide them again, do as following

1. Open Terminal

2. Issue command

defaults write com.apple.finder AppleShowAllFiles –bool false

3. Kill the Finder to take effect by issuing the command

killall Finder