Glossary · AI & Data

Prompt Engineering

Prompt engineering is the practice of designing and refining instructions, context, and examples so an AI model produces reliable, useful output.

Updated October 6, 2026

Prompt engineering is the iterative practice of writing and testing prompts so a language model behaves consistently for a given task. It covers instructions, examples, output formats, and how context is arranged.

Why it matters

A well-built prompt can replace more expensive options like fine-tuning and makes outputs easier to parse and validate. Because models change between versions, prompts used in production need regression tests.

Example

Common techniques include giving a role, supplying examples (few-shot prompting), and demanding a structured format:

Classify the ticket as "billing", "bug", or "other".
Return JSON: {"category": "...", "reason": "..."}

Ticket: "I was charged twice this month."

Asking for JSON lets your code validate the answer and retry when it is malformed.

Common mistakes

  • Judging a prompt from a single try instead of a set of varied test cases.
  • Making prompts long and contradictory rather than clear and minimal.
  • Trusting the output without validation, since the model can still hallucinate.

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