Choosing the right software
Software is a program that does a job. Pick the one made for your job.
- Word processor: letters, essays, reports.
- Spreadsheet: tables of numbers, sums, charts.
- Presentation app: slides for a talk.
- Image or sound editor: photos, drawings, audio.
- Simulation: a computer model of something real, like a falling ball or traffic. You change inputs and watch what happens. It is safe, cheap and fast, but it is only as good as its model.
Learning a new tool works best by trial and error: try, look at the result, change one thing, try again. Use help pages and free tutorials.
File formats and compatibility
A file format is the rule for how data is stored. The extension after the dot tells you the format: .txt, .pdf, .png, .jpg, .csv, .mp3.
Compatibility means a file opens correctly on other devices and apps.
- Open formats have public rules. Any app may read them (PDF, PNG, CSV, TXT, ODT). Good for sharing and for keeping files for many years.
- Closed (proprietary) formats belong to one company. They may open badly, or not at all, elsewhere.
Tip: edit in your app's own format, then export a PDF to share a final copy. Use JPG for photos and PNG for logos and screenshots.
Sharing and versioning teamwork
Teams can keep one file in cloud storage (files kept on online servers). Everyone edits the same copy, so there are no emails with "final_final2".
- Version: a saved state of the file. Version history lets you go back.
- Permissions: choose who can view, comment or edit.
- Use clear file names like
project_report_2026-10-01.pdfand folders by topic. - Keep a backup: a second copy in another place.
How search engines work and checking sources
A search engine works in three stages:
- Crawl: programs called crawlers visit pages and follow links.
- Index: words from pages go into a huge list, like the index at the back of a book.
- Rank: for your words, it orders pages by things like match, links from other sites and freshness. Ads may appear on top.
A high rank is not proof. Check each source: Who wrote it? When? What proof does it give? Does another trusted source say the same? Use exact words, quotes and the site filter to search better.
Licences, reuse and digital culture
A licence is the permission that comes with a piece of work.
- Free / open-source software: you may use, study, change and share it (for example Linux, LibreOffice, Firefox).
- Proprietary software: the owner keeps the rights; you usually buy a licence to use it only.
- Creative Commons (CC): lets creators share pictures, music and text with simple rules, such as BY = give credit, NC = no business use.
- Public domain: no rights left; anyone may reuse.
Milestones: mechanical calculators (1600s), programmable machines and first electronic computers (1940s), personal computers (1970s–80s), the World Wide Web (1989–91), smartphones (2000s), everyday AI (2020s). Today, new ideas like AI (programs that learn from data) and blockchain (a shared record that is very hard to change) also raise questions about privacy: what data we give and who keeps it.
Key formulas and definitions
- Right tool → right job
- Open format = public rules = opens almost anywhere
- Version history = undo for the whole team
- Search = crawl → index → rank
- Check a source: Who? When? Proof? Elsewhere?
- Reuse = read the licence + give credit
Worked examples
1. You must send your final report to a teacher who uses a different computer and a phone. Which format?
Export it as PDF. PDF is an open format and keeps the layout the same on every device.
2. A website says "Drinking 10 litres of water a day makes you taller." It has no author and no date. Is it reliable?
No. Who wrote it is unknown, there is no date, no proof and trusted health sites do not say this. Do not share it.
3. You want a picture for your poster. It is marked CC BY. What must you do?
You may use it, but you must give credit to the creator (name and source).
Common mistakes
- Thinking the top search result must be true. Rank is not truth; check the source.
- Sending a file in a format only your app can open. Export to an open format like PDF.
- Saving over the only copy. Keep versions and a backup.
- Thinking "free to download" means free to reuse. Read the licence and give credit.