Files, folders and file types.
"Where did I save that file?" is one of the most common office problems. Today you'll learn how files and folders work, what file extensions mean, and a simple system to keep your work organised forever.
Files and folders
- A file is one saved item: a document, photo, song, video.
- A folder holds files and other folders, like an almirah with shelves.
- The path shows where a file lives:
C:\Users\Ayesha\Documents\College\Semester 5\Project.docx
File extensions
The letters after the dot tell you the type of file:
| Extension | Type | Opens with |
|---|---|---|
| .docx | Word document | Word, Google Docs, LibreOffice |
| .xlsx | Excel spreadsheet | Excel, Google Sheets |
| .pptx | PowerPoint presentation | PowerPoint, Google Slides |
| Fixed document (looks the same everywhere) | Any browser or PDF reader | |
| .jpg / .png | Images | Photos, any browser |
| .mp4 | Video | Any video player |
| .mp3 | Audio | Any music player |
| .zip | Compressed folder | Built into Windows and phones |
| .exe / .apk | Programs (Windows / Android) | Be very careful: only from trusted sources |
In Windows File Explorer, turn on View → Show → File name extensions. Then you can spot tricks like "invoice.pdf.exe" (a program pretending to be a PDF).
A simple folder system
Documents
├── College
│ ├── Semester 5
│ └── Certificates
├── Jobs
│ ├── CV
│ └── Applications
├── Personal
│ ├── ID copies (keep safe!)
│ └── Bills
└── ProjectsName files professionally
| Bad | Good |
|---|---|
| final final new (2).docx | Ayesha_Fatima_CV_2026.pdf |
| doc1.docx | Sales_Report_Oct_2026.docx |
| IMG_20261103.jpg | Aadhaar_front.jpg (and store it safely) |
Use Name_Topic_Date, no spaces or with underscores, and dates as Year-Month (2026-11) so they sort correctly.
Compress and convert
- Zip many files into one: right-click → Compress to ZIP (Windows).
- Save as PDF before sending documents that shouldn't change: File → Save As → PDF.
- Reduce photo size for forms that limit file size: use free online compressors or your phone's editor.
You need to send your CV to a company. Which format is usually best?
PDF keeps formatting identical on every device; a clear name looks professional.
Module 1 test
In the IPOS cycle, what is "storage"?
Input, Process, Output, Storage.
Which part is the computer's short-term working memory?
RAM is temporary working space.
The safest place to download apps is…
Official sources only.
Which file type looks the same on every device?
PDF preserves layout.
Your task (20 min)
Create the folder system above in your Documents (or Google Drive). Move your scattered files into it and rename 10 files using the Name_Topic_Date pattern. Turn on file extensions in Windows.
Lesson 4 complete!
You can organise files and folders, recognise common file types, name files professionally, and compress or convert files. You finished Module 1!
Next: How the internet works →