Computer File Extension

What is File Extension?

A file extension is actually a suffix to a computer file name used in an operating system such as Linux, macOS, and Microsoft Windows. Ideally, it can be classified as a specific form of metadata.

A complete file name ideally will comprise the name of the particular file as well as the extension. This extension normally has three to four characters but in some rare cases there can be even one or two characters, and it is typically separated by a dot symbol.

Understanding Computer File Extension and Its Types

What is File Extension

An extension added with the file name typically identifies the file. It facilitates the operating system in understanding the distinctiveness of the file, and the intended use, to some extent.

A file extension helps the operating system as well as the users primarily in two specific ways such as:

For example, if a file is named as ‘birds_picture.webp’ it means that it has a ‘jpg’ file extension.

In Windows, when you click on the file, the operating system will search for all those apps that are relevant to JPG files and will open the app first in order to load the file containing images of birds.

And, on the other hand, for a text file named as readme.txt, Windows will know that it is a text file due to the TXT suffix in it and open the file with the default text editor.

Showing the file extensions is not only helpful but it also adds to the security aspect.

This is because without these extensions being shown it would be hard, if not impossible, for a user to tell whether the PDF file they are looking for, for example, is actually a PDF file and not any malicious file.

Different operating systems follow different ways and policies when it comes to showing the file extensions. Here they are.


In Windows, file extensions are shown by default. Yes, you can see these even in Windows 7, 8, or 10 though these versions had changed it for some time, but fortunately, things are back to square one.

However, sometimes, the file extensions may not be visible on Windows, which is not an error of the operating system.

No matter whatever is the reason, you can easily turn it back on in Windows. The steps to follow in this case are:


In macOs however, file extensions are not shown by default. This is because the way in which the file extensions used in this particular operating system is not the same as the ways used in Windows.

However, you can make some slight changes so that you can see the file extensions on Mac. The steps to follow in this case are:

Both macOS and Linux do not rely on file extensions as heavily as Windows does.

Rather, these operating systems use the creator codes and MIME or Multipurpose Internet Mail Extension, which is an internet standard to encode file formats that are used by email programs, to determine the file type they are supposed to deal with.

This information is typically found on the header of the file.

This means that, in macOs and Linux operating systems, you can have a file with no extension in it and it may still be valid, as opposed to Windows operating system.

Therefore, changing or deleting file name extensions should be done according to the operating system that you are using.

For example, if you delete a file name extension in Windows, the operating system will not know what exactly is to be done with the file anymore.

In that case, Windows will ask you which particular app you want to use to open that specific file.

On the other hand, if you delete a file extension in macOS in the Finder, the operating system will add the same right back by using the data available in the MIME type of the file.

However, if you change a file extension, for example ‘birds.webp’ to ‘birds.txt’ in Windows, the operating system will use an app to open the file which is relevant to the new extension such as Notepad. Two things may happen in this case such as:

It is for this reason you are warned by Windows whenever you want to make changes in the file extension and want your confirmation if you still want to proceed with your action.

The same thing happens in the case of macOS and Linux operating systems as well, even though both of these operating systems do not use file extensions exclusively to handle a file.

Typically, a file extension can be changed successfully by using specific types of software programs that are capable of converting it.

File extensions can be given to all types of files such as:

You will find a more detailed list in the later section.

So, now you may ask what should be the length of a file extension in Windows so that it is considered to be a valid one. Well, it should never be more than the maximum file name character limit of Windows.

This limit may however vary a little bit depending on the version of the Windows operating system you are using.

The file name character limit of Windows 10 is 260, which is the same for Windows 8, Windows 7 and Windows Vista.

However, for Windows XP, it is 255 characters and for Windows 2000, the character limit is up to 254.

Now, finally, take a look at the different types of extensions used against the name of a computer file.

Typically, there can be thousands of different file extensions that can be related with one or more apps, in fact, way too many to include all in one article.

So, here are the ones that are most commonly used along with their respective purposes.

For Archived and Compressed Files:

For Physical Recordable Medium Archiving:

For Computer Aided Design or CAD:

For Electronic Design Automation or EDA:

For Database:

For Desktop Publishing:

For Document:

For Financial Data:

For Font Files:

For Geographic Information System of GIS:

For Graphical Information Organizers:

For Graphics Color Palettes and Management:

For Raster Graphics:

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For Vector Graphics:

For 3D Graphics:

For Links and Shortcuts:


For Executable Files, Object Codes, Dynamically Linked and Shared Libraries:

For Page Description Language:

For Personal Information Manager:

For Presentation:

For Scientific Data Exchange:

For Programming Scripts and Languages:

For Security Keys and Certificates:

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For Non-audio Signal Data:

For Sound and Music:

For Computer Program Source Codes:

For Video:

For Web Page:

For Different Web Standard Formats and Markup Languages:

For Generic Files:

These file extensions are reused often with no particular format or different formats by several programs.

For Others:

As said earlier, this is just a modicum of the file extensions. Factually, there are thousands of them available out there and used.

There are several other file extensions for different video game data and storage, and virtual machines along with other generalized files.

If you want to know about all those names and their meaning, look for articles that tell about the file name extensions and their full forms.

Finally, a word of caution: Play safe when you open files and do not open any that comes from unknown or unreliable sources.

Be informed that there are lots of file types and extensions out there that may be potentially risky and dangerous because these executable files can run specific codes when you open them.


The computer file extensions are the identifier of a file that the operating systems use to recognize it.

As this article points out, there are different types of file extensions that are of utmost importance and therefore should not be changed.