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File extensions

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You have already learned that the file extension is the part of the filename that comes after the period, and how to display it on your own machine. Now we will look at why it is useful to recognize file extensions, and how to use them correctly yourself.

Have you turned on file extensions?

Check a file in your folder structure now — can you see .docx, .jpg, or something similar after the name? If not, go back to [[Folder Structure Level 2 - File Names|previous part]] and turn it on first.

File extensions in IT and media production

Different fields use different file types. Here are some you will encounter at IM:

Extension What is it? Field
.py Python script IT
.html / .css Web page / stylesheet IT
.js JavaScript code IT
.docx Text document Both
.pdf Finalized, locked document Both
.jpg / .png Image Media Production
.psd Photoshop project file Media Production
.mp4 Video file Media Production

File extensions for code, documents, images, project files and video

Working file vs. final file

A .psd file is not the same thing as a finished .jpg – one is the working file you can still edit, the other is the final result.

The same logic applies to code: a .py file is the source, not itself a finished, runnable program.

A working file can be further edited, while the final file is the result that is delivered

Overview of file extensions, working files and final files

Example of packaging and finding files

Task - Create correctly named files in your own folder structure

You are to submit three files for a school project: an image, a text document, and a website file.

Step 1 - Create the files

Go into the folder structure you created in [[Folder Structure Level 1 - Create a Folder Structure|Folder Structure Level 1]], and create three new, empty files:

  • one image file (.jpg or .png)
  • one text document (.docx)
  • one web page file (.html)

Step 2 - Give them proper names

Each file should have:

  • a descriptive name (see [[Folder Structure Level 2 - File Names | previous part]])
  • correct file extension for the content type
  • correct placement within its own folder structure

Don’t change file extensions to “trick” a program

The file extension should match its actual contents. Changing .docx to .html does not turn the file into a web page—it just corrupts it for the program that’s supposed to open it.

Step 3 - Check your work

Review your three files. Is the file extension visible on all three? Do they have names that tell what they contain without having to open them?

- If you are done

Look at the filename IMG2093.jpg. Is this a good filename? What would you name the file instead, without changing the file extension?

Done! 🎉

You now recognize common file extensions within IT and media production, and know the difference between a working file and a finished file. Combined with good naming conventions from the previous part, you now have what you need to keep your schoolwork organized for the rest of the year.