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Your computer has many different types of files on it, and each one has its own file extension. A file extension is a three- or four-letter identifier found at the end of a file name and following a period. These extensions tell you about the characteristics of a file and its use. In this lesson, we'll go over some examples of these extensions, as well as how to determine a particular file's extension.
Examples of file extensions
- A JPEG uses the .jpg or .jpeg extension (for example, image.jpg).
- A Word document uses the .docx extension, or .doc for older versions (for example, CoverLetter.docx).
- An MP3 audio file uses the .mp3 extension (for example, rhyme_rap.mp3).
- An Excel spreadsheet uses the .xlsx extension, or .xls for older versions (for example, budget.xls).
Hidden file extensions
Some operating systems hide file extensions by default to reduce clutter. It is possible to show the file extensions if they're hidden. Click the links below to see how to show file extensions in Windows and macOS:
You can also usually tell what the file type is by looking at the file's icon. For example, the Word document looks like a file with a W in the corner, while an Excel spreadsheet looks like a file with an X in the corner.
File extensions also tell your computer which applications to use when opening that file.
A file type is a name given to a specific kind of file. For example, a Microsoft Word document (.doc, .docx, etc.) and an Adobe document (.pdf) are two different file types. While these file types are associated with individual applications, other file types, such as rich text RTF files and MP3 audio files are standard file types that can be opened by multiple programs.
OneDrive tips!
- Back up your files using OneDrive - It is a great idea to back up your files to prevent losing your work. If you're still carrying around a flash drive, USB or thumb drive or any other portable file storage option, try using OneDrive to save your files to the cloud!
- Tons of storage for your files! Sierra College students have 1T (one terabyte) of storage in OneDrive through Microsoft Office 365.
- Need to scan a file? Scan files by using your phone and the OneDrive app.
Want to preserve your formatting? Please first verify that a PDF file is acceptable for your assignment, then review these steps to Save As or Create a PDF
Need to change a file type?