Prompt engineering is the practice of crafting effective instructions for AI models to get the best possible output. A well-engineered prompt includes context (who you are, what you need), specific instructions (what format, what length, what tone), examples (if available), and constraints (what to avoid). The difference between a mediocre AI output and an excellent one is almost always the quality of the prompt, not the model. It is the single most valuable AI skill for non-technical professionals.