Prompt engineering is writing instructions for an AI model carefully enough that it gives you what you want reliably, not just once by luck.
Prompting changes behaviour per request and costs nothing to alter. Fine-tuning changes the weights permanently.
Prompt engineering is the practice of writing instructions for an AI model so that it produces what you want consistently. The emphasis is on consistently.
Anyone can get a good answer once. Getting the same quality on the hundredth request, from a hundred different users, is the actual work. That means testing, comparing, and iterating rather than wordsmithing.
Think of it like this. Think of briefing a capable contractor who takes everything literally and never asks questions. Vague instructions get a technically valid result you did not want. The fix is a clearer brief, not a smarter contractor.