When you double-click, say, a .docx file, Windows checks to see what application is associated with that extension (probably a word processor) and opens the file in that program.

Red Eye Rose received a file with a strange extension. She doesn't know into what program she should load it. Neither does Windows.

Learn how to rename all file extensions in a folder & sub-folders at once on Windows 11/10. You can batch rename or rename all file extensions in bulk using this guide.

Mac OS X computers use a default application to open every file type based on its file extension. If you don't want to use the default application when opening a file, you can select "Open With ...

In iOS 16.0 and later, you can make Apple's stock Files app display file extensions for items in the currently viewed folder. Keep reading to learn how it's done. The only issue until recently was ...

Google today released a new Chrome extension for Google Drive aimed at making it easier to open files right from the correct desktop application.