What Is a Prompt and Why It Matters

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A prompt is an instruction for artificial intelligence — the text you use to tell ChatGPT, Claude or another AI tool what to do. It can be a question, a command, or a whole structured brief with context and examples. The quality of the prompt determines the quality of the result more than the AI model itself.

I see it all the time. Someone tries ChatGPT, gets a mediocre result and declares: "AI is overrated." But the problem isn't the AI — it's how you talk to it. And that's the single most important skill you'll learn working with AI.

 A prompt is simply what you type to the AI. But just as it matters how you phrase a question to your doctor, it matters how you phrase an instruction to AI. 

Bad prompt vs. good prompt

Let me show you the difference with a concrete example. You want to write an e-mail to a customer waiting for a delayed order.

⚠ Bad prompt

"Write an e-mail to a customer about a delayed order."

✓ Good prompt

"Write an e-mail to customer John Smith. He ordered trainers (order no. 4821) that were due to arrive on Friday. They're delayed by 3 days due to carrier issues. The tone should be friendly and apologetic. Offer a 10% discount on the next purchase as compensation. Max 100 words."

Both prompts are plain English. Both ask for an e-mail. But the results are worlds apart.

5 rules of a good prompt

1. Say who you are and who the recipient is

The AI doesn't know you run a children's clothing e-shop and you're writing to a 35-year-old mum. Tell it.

2. Specify format and length

"Write it as bullet points", "three sentences max", "LinkedIn post format" — these instructions dramatically improve the result.

3. Give examples

Show the AI what you like. "Here's an example of an e-mail we sent before — write in a similar style." The AI learns your voice. That's exactly how RAG knowledge systems work, too — the AI has access to your data and answers from it.

4. Say what you don't want

"No marketing phrases", "don't use the word synergy", "no needless apologies" — negative instructions are as powerful as positive ones.

5. Iterate

Result not good? Don't delete everything and start over. Continue: "Make it sound less formal" or "Cut it in half but keep the main point." The AI remembers the context of the conversation.

💡 The golden rule

The more precise the instruction, the more precise the result. If you gave the same brief to a temp and they wouldn't know what to do — the AI doesn't know either.

Why this matters more than choosing an AI tool

People argue whether ChatGPT or Claude or Gemini is better. That's like arguing whether Bosch or Makita is better — what matters is whether you know how to drill.

A good prompt pulls an excellent result out of an average AI tool. A bad prompt pulls an average result out of the best AI tool.

Learn to write good prompts. That's an investment that pays off no matter which AI tool you'll be using a year from now.

Want AI for your business? Write to me.

Written by Dušan Kníže

AI developer · Prague, Czech Republic

I build AI solutions for businesses — from chatbots to knowledge systems. I write about what actually works, no buzzwords. More about me →