By default, some files are hidden in Mac OS X. Example, if you need to upload or edit .htaccess file, you can't find it in Finder and you can't see it in FTP program.

To show all hidden file, you need to turn it on from Terminal .

Click LaunchPad > Other > Terminal

Then type the following and press Enter

defaults write com.apple.finder AppleShowAllFiles YES

Open the Finder again and you should able to see the hidden files.

To hide the hidden file, just run the following command in Terminal.

defaults write com.apple.finder AppleShowAllFiles NO