Common mistake Capitalize file extensions

Common Grammar Mistake: Not Capitalizing File Extensions

When it comes to files and their extensions, one common grammar mistake that is often overlooked is the failure to capitalize the file extension. File extensions are the letters that follow a period at the end of a file's name, indicating the file type. For example, in the file name "document.docx," the file extension is ".docx."

The Importance of Capitalizing File Extensions

File extensions are typically capitalized, and not capitalizing them can lead to confusion and potential compatibility issues. Capitalizing file extensions is not just a matter of aesthetics; it serves a functional purpose.

  • Consistency: Capitalizing file extensions helps maintain consistency across different operating systems and software applications. Regardless of the system or application being used, capitalizing the file extension ensures that it is recognizable and can be read correctly.
  • File Type Identification: Capitalizing file extensions makes it easier to identify the type of file at a glance. For example, ".DOCX" indicates a Microsoft Word document, while ".PNG" signifies a portable network graphic image.
  • Compatibility: Some applications and operating systems are case-sensitive when it comes to file extensions. If a file extension is not capitalized correctly, it may not be recognized or opened by certain programs or platforms.

Examples of Correctly Capitalized File Extensions

Here are some examples of commonly used file extensions and how they should be capitalized:

  • .DOCX (Microsoft Word)
  • .PDF (Portable Document Format)
  • .JPEG or .JPG (Joint Photographic Experts Group)
  • .PNG (Portable Network Graphics)
  • .XLSX (Microsoft Excel)
  • .PPTX (Microsoft PowerPoint)
  • .HTML (Hypertext Markup Language)

Additionally, it is worth mentioning that tools like Linguix grammar checker can be incredibly helpful in detecting and fixing such grammatical errors in your writing.


Capitalizing file extensions is a crucial aspect of maintaining proper grammar and ensuring the clarity and compatibility of your files. Remember to capitalize file extensions consistently in order to avoid confusion and compatibility issues across various platforms and applications.

Capitalize file extensions mistake examples

  • Incorrect:
    Please see the attached pdf.

    Please see the attached PDF.

Linguix Browser extension
Fix your writing
on millions of websites
Linguix pencil
This website uses cookies to make Linguix work for you. By using this site, you agree to our cookie policy