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File Extensions Brief Introduction

Updated on Thursday, December 19, 2024

Written by

Sherry Song

Approved by

Jessica Shee

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Summary: There are so many file extensions in our life and work. But do you really know what they are? Today, let iBoysoft walk you through the simple introduction of file extension.

 

In daily usage, file extensions are used so widely in computing. A file extension is a suffix attached to the end of a file name that indicates the file type or format. This often consists of a period followed by a series of letters and is used by operating systems and apps to understand how to process, open, or interact with the file.

For example, the “.txt” file extension suggests a plain text file, while “.jpg” denotes an image file. Learning file extensions can be highly beneficial for managing and using files effectively.

What is the purpose of a filename extension?

The primary purpose of a filename extension is to inform both users and computer systems about the nature of the file's content. This allows the operating system to associate specific programs with specific file types, facilitating seamless user interaction.

When a user clicks on a file, the system refers to its filename extension to determine which application should be used to open it. Without extensions, file handling would be considerably more complex, as the operating system would have to analyze each file's internal structure to determine its type.

File extension common examples

Maybe you know .jpg .doc .xls..., how about other computer file extensions? File extensions span a wide range of categories, reflecting various file formats. Here are some common examples:

  • Document files: .docx (Microsoft Word), .pdf (Portable Document Format), .txt (Plain Text)
  • Spreadsheet files: .xls (Microsoft Excel), .csv (Comma-separated values), .ods (OpenDocument Spreadsheet)
  • Image files: .jpg or .jpeg (JPEG image), .png (Portable Network Graphics), .gif (Graphics Interchange Format), .raw (Photoshop raw file), .tiff (Tagged Image file format)
  • Audio files: .mp3 (MPEG Layer 3 Audio), .wav (Waveform Audio), .flac (Free Lossless Audio Codec)
  • Video files: .mp4 (MPEG-4 Video), .avi (Audio Video Interleave), .mkv (Matroska Video)
  • Compressed files: .zip (Compressed Archive), .rar (Roshal Archive), .7z (7-Zip Archive)
  • Executable files: .exe (Windows Executable), .bat (Batch File), .sh (Shell Script)

These file extensions help distinguish the purpose and capabilities of different files, making it easier for users to interact with their content. Share this summary to help more people.

 

How file extensions work

When a file is saved or created, the operating system often appends a file extension automatically based on the format chosen by the user or the software in use.

For example, saving an image in a photo editing program may add a ".jpg" or ".png" extension based on the selected settings. Upon attempting to open the file later, the operating system reads the extension and matches it with an installed application, such as a media player for a ".mp3" file or a web browser for ".html".

If a user tries to open a file with an unrecognized or missing extension, they may encounter errors or be prompted to select an application manually. Thus, filename extensions simplify and streamline the file-handling process, saving both time and effort.

How to change and customize file extensions

It is possible to change a file extension manually, though this should be done with caution. Renaming the extension does not alter the underlying file format; rather, it merely changes how the system or associated applications interpret it.

For instance, changing a ".txt" file to ".docx" may not instantly make it compatible with word processing features. 

So how to change the file extension? You can:

  • Ensure file extensions are visible (this can be enabled via the "View" settings in most operating systems).
  • Rename the file, changing the characters after the period (e.g., "file.txt" to "file.csv").
  • Confirm the change when prompted, as it may affect how the file is accessed.

For more customized handling, conversion tools can be used to properly change the file format while adjusting the extension accordingly. This ensures compatibility and usability without potential errors from mismatched extensions.

If you feel this post is useful, why not share it to help others know what is a file extension?