If you are a IT administrator or pretty much anyone who works with computer files a lot, then you are probably aware that by default these file extensions are always hidden. If you are reading this article, you may not agree with that situation. You probably also know that the place to enable viewing file extensions changes with each major OS release. I created a TechNet Wiki article a while ago that explains how to enable them and just updated it for Windows 8 and Windows Server 2012.
What's the big change for Windows 8 and Windows Server 2012? Press the Windows Key + X and then click File Explorer. Click View and then see the checkbox that reads File Name Extensions. You can also click that Folder icon in the Desktop view taskbar to open File Explorer.