Use These Settings to Show or Hide Filename Extensions
On the Mac, nearly every file has an *extension*, a set of characters after a period that indicates what type of file it is and determines which app opens it. So, **.png** indicates a PNG graphic that opens in Preview by default, **.pages** denotes a Pages document, and **.docx** identifies a file as belonging to and opening in Microsoft Word. Plus, the extension for all applications is **.app**. Depending on what you do, how often you exchange files with people on other platforms, and your personal preference, you may wish...