What is a file extension and how does it help identify a file?

• A. The suffix after a dot indicating file type and associated program.
• B. The prefix before a dot indicating the author.
• C. The file size written after the name.
• D. A metadata tag indicating the creation date.

Answer: (A)

The suffix after the last dot in a file name is the file extension. It signals what kind of data the file holds and which program should open or handle it. This helps the operating system and applications quickly identify how to read the file, display it, or edit it. For example, extensions like .txt indicate plain text files, .jpg or .png indicate images, and .docx indicates a Word document. The extension acts as a hint about the file’s format, guiding default actions and compatibility. Keep in mind some files can lack an extension or have a misleading one if renamed, so the extension isn’t a perfect guarantee of content.