File names, and what the ending tells you
Look at any file name and know what it is before you open it.
Nearly every file name comes in two parts: the name somebody chose, then a full stop, then two to four letters saying what sort of file it is.
In Water bill 2026.pdf, the name is Water bill 2026 and the ending is pdf. The two parts have completely different owners.
There are hundreds in existence and about eight that matter in an ordinary week.
Key points
- A file name is your part, a full stop, and the computer’s part
- .pdf is a document, .jpg a photograph, .docx something written, .exe a program
- Changing the ending does not convert a file — it only confuses the computer
- Rename freely: good names are the ones you would say out loud
What to remember
- The ending is a label on a parcel. Read it first, every time, and you never have to open something to find out whether it was safe to open.
- Read the ending before you open an attachment. It is the nearest thing a computer has to a label on a parcel.
- You have now read six files without opening a single one. The ending told you everything.
- Name a file with the words you would use out loud. Those are the words you will type into a search box later.
Try this
Find one file on your own machine with a meaningless name — a photograph, or something a bank sent you — and rename it into plain English. Right-click it and choose Rename. Leave the ending exactly as it is.
Practice: File names, and what the ending tells you. Your first lesson is free, with no account or card; the rest are part of a Lantern plan. Interactive lessons require JavaScript.