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...