Types and Extensions
Every file on your computer has a name and a special ending called an extension. The extension tells the computer what kind of file it is and which program should open it.
What is a File Extension?
A file name has two parts separated by a dot. The part before the dot is the name you give it. The part after the dot is the extension — it shows the file type. Example: myStory.docx
myStory.docx
myStory = file name | .docx = extension (Word document)
Common File Types
| Extension | File Type | Opens With |
|---|---|---|
| .docx | 📝 Word Document | Microsoft Word |
| .txt | 📄 Plain Text | Notepad |
| 📕 PDF File | PDF Reader / Browser | |
| .jpg / .png | 🖼️ Image | Photos / Paint |
| .mp3 | 🎵 Music | Media Player |
| .mp4 | 🎬 Video | Video Player |
| .xlsx | 📊 Spreadsheet | Microsoft Excel |
| .pptx | 📑 Presentation | Microsoft PowerPoint |
| .zip | 🗜️ Compressed Folder | File Explorer |
Spot the File Icons
💡 Never rename a file's extension (the part after the dot) unless you know what you are doing. Changing it can stop the file from opening.
Quick Exercise
Q1. A file is named holiday.jpg. What type of file is it?
✅ It is an image file. The .jpg extension means it is a photo or picture.
Q2. Which extension shows a music file?
✅ .mp3. It opens in a music or media player.
Q3. What are the two parts of a file name, and what separates them?
✅ The name and the extension, separated by a dot (.). Example: story.docx
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