Prompt engineering is just writing good instructions for AI. The name sounds technical, but it is a skill anyone can learn: say who the AI should be, what you want, the context it needs, an example, and the shape of the answer. Clear in, useful out.
It matters because the prompt is the biggest lever you control. Same model, better instructions, better result. And it is not one-and-done: you write, read, steer, and repeat (iteration).