See all Apple Hidden Files I came from Windows 2 years ago and I knew there were hidden files in all OS's. As Windows has the simple option to show them to you, I supposed that if I contacted Apple support they would tell me how to show hidden files. But they simply told me they didn't exist at Mac OS. So I had to find the answer myself.

But today I was browsing some files with the terminal, I did ls -l -a to see all files (including those hidden) in a list and I saw kind of a different file that began with a dot and an underscore (._). I could see in the Finder all files except that one. 

So my question is: Why can't I see that file (e.g. ._hello) in the Finder if I have already configured it to show me all files, including the hidden ones? Is that another kind of hidden file which I'm not aware of?
There are 2 kinds of hidden files on OS X.

Files starting with . are normally hidden in Unix (including OS X) or Linux systems, but can easily be shown e.g. by ls -la.

In addition certain files (or directories) are hidden by OS X apps ( ~/Library is one example) and generally files inside bundles (such as .apps) are not normally visible.

It is easy to show hidden files in Finder (by changing settings defaults write com.apple.finder AppleShowAllFiles TRUE). This then applies to all files.

Finder addons such as TotalFinder make changing this easier and Finder alternatives such as QuollEyeTree http://binnie.id.au/QuollEyeTree.html let you toggle this for individual directories and show both kinds of hidden files.