Windows natively packs a ton of useful features that are either hidden or disabled by default, even though they're more than good enough to be enabled at first launch. Windows hides file extensions by ...
I use my Mac in a multi OS environment (i.e. with Windows) and whenever I take a screenshot (Cmd-Shift-4) intended for a PC user, I have to go to information and tell the OS not to hide the extension ...
Microsoft hides file extensions in Windows by default even though it's a security risk that is commonly abused by phishing emails and malware distributors to trick people into opening malicious files.