Tech Explained: 11 Technologies, Simply (FREE) with Raghu Datta

You use UPI, OTPs, QR codes, Google and Instagram every day. This free guide explains how eleven of these everyday technologies actually work, in simple English, so you can explain them in a first technical interview.

Each chapter starts with a local analogy (a waiter, a railway station master, a cheque, a canteen token, a library register), then gives the real steps in order with the correct terms, where you meet it, one hands-on thing to try tonight on your own phone or laptop, copy-paste AI prompts to go deeper, and three interview-style questions with short model answers.

Inside: what an API is; what Linux does; how a website loads (DNS, the resolver hops, the Network tab); how Google ranks results; how the Instagram feed chooses; what open source is; what a QR code stores; how a UPI payment works; what an OTP is and why it expires; how passwords leak and how 2-step verification helps; public Wi-Fi and what a VPN does. Plus a two-week practice plan and a printable explain-it checklist.

Free, 39 pages, phone friendly, drawn illustrations throughout.

What you'll learn:

Eleven technologies, one method: Picture it with a local analogy, learn the real steps, try it tonight, explain it out loud. The same four steps in every chapter.

11 things to try tonight: Call a free weather API, type Linux commands in your browser, open the Network tab, find a UPI reference number, turn on 2-step verification and more. All free.

18 copy-paste AI prompts: Prompts that make a chat assistant read your results with you, quiz you, build tiny Python examples and role-play support calls.

33 interview questions: Three per chapter, with short model answers you can say in one breath: what DNS is, what a 404 means, how passwords should be stored.

Security, explained calmly: OTPs, password storage, 2-step verification, HTTPS and VPNs explained technically, with sources, and what to switch on today.

A two-week plan and a checklist: One technology a day, if-then rules for when you fall behind, and a printable checklist of what you can explain.

FAQs:

Do I need to know coding?

No. Every chapter works without coding. A few optional prompts show tiny Python examples if you want to go further.

Which AI tool do I need?

Any AI chat assistant works: ChatGPT, Gemini, Claude, Copilot or another. The free versions are enough.

Will this help in interviews?

Yes. Each chapter ends with three interview-style questions and short model answers for developer, testing, support and cloud roles.

Is it really free?

Yes. Download it, use it, and share it with a classmate.