The export that will not send
An analyst exports a year of shop sales. The email bounces: "attachment too big". At the next desk, an old computer takes a minute to open one results file.
Both are small jobs for the helper programs that come with a computer. Today you meet three of them.
Key words
| Word | What it means | Example |
|---|---|---|
| Utility | a small helper program that looks after the computer | |
| File management | making, naming, moving, copying and deleting files and folders | |
| Compression | making a file smaller so it uses less space | a ZIP file |
| Lossless | compression that loses nothing: the file comes back exactly | |
| Lossy | compression that throws some detail away | a JPEG photo |
| Fragmented | split into pieces stored in different places | |
| Defragmenter | a utility that puts the pieces of files back together | |
| Operating system | the main program that runs the computer |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can say what file management, file compression and a defragmenter do and when to use each.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
File management keeps files in order
A utility is a small helper program. File management is the one you use most. It lets you make, name, move, copy, rename, search and delete files and folders.
Good habits make files easy to find: clear names, one folder for each project, and no copies left lying about. A path such as Projects/Survey/raw.csv shows where a file lives.
Everyday file jobs for an analyst
| Job | What happens | A good habit |
|---|---|---|
| Create | A new file or folder is made | Name it clearly at once |
| Move | The file goes to another folder | Keep raw data and cleaned data apart |
| Copy | There are now two of the file | Delete the extra one when done |
| Rename | The name changes, the contents do not | Put the date first, year then month then day |
| Delete | The file goes to the bin or is removed | Check the bin before emptying it |
The cells students fill in are left blank in this preview.
Compression makes files smaller
Compression squeezes a file so it uses less space. It sends faster too. A ZIP file holds many files in one smaller package.
Lossless compression loses nothing: unzip it and you get the exact original. That matters for data, where one lost digit is a wrong answer. Lossy compression throws away detail you will hardly notice, so a photo or song becomes much smaller. You cannot get the lost detail back.
Extra: Make a sales file with lots of repeats
yes "2026-10-01,north,tea,3" | head -5000 > sales.csvA command for the lesson’s lab terminal. It is shown here and not run.
Extra: Compress it
gzip -kf sales.csvA command for the lesson’s lab terminal. It is shown here and not run.