Show all/hidden files in the Finder

By default, you can't see many system files, dot files and folders in Finder, you only see them in the Terminal using de ls command.
If you need to see them, do this:

-> Open the Terminal App, inside Aplications - Utilities
-> Type: "defaults write com.apple.Finder AppleShowAllFiles YES" and press Enter
-> Restart the Finder App, press option + alt + esc
-> Select Finder
-> Press Force Quit

To hide again this system files and folders, repeat the process but type "defaults write com.apple.Finder AppleShowAllFiles NO" instead.