Today we have a simple trick to show the file extensions for any file. In very old versions of Mac’s and PC’s showing a files extension is the norm. However in later versions of Mac OS X this has been hidden. If you want to get it back so you can understand what type of files you are dealing with, we can. It is a simple change that doesn’t take very long and is very simple to switch on and off.
To turn on file extensions open up Finder. Within the menu bar select Finder > Preferences. From the dialog box select the Advanced tab.
From the myriad of options select the ‘Show all filename extensions’ from the list. This will subsequently make file extensions visible within all windows within Finder.