Structured prompts are essential tools in prompt engineering because they specify the exact format you want in an AI's response. By including explicit formatting instructions—such as requesting Markdown, JSON, or bullet lists—you ensure that the output is clear, consistent, and easy to use or process. This is especially important when you need to extract information programmatically or want the response to be easily readable.

To illustrate the difference, consider the following comparison of unstructured and structured prompts:

• Unstructured prompt: List the benefits of exercise;
• Structured prompt: List the benefits of exercise as bullet points in Markdown;
• Structured prompt: Provide the answer as a JSON object with keys 'benefit1', 'benefit2', and 'benefit3'.

These kinds of prompts guide the AI to produce organized, predictable outputs, which is crucial for clarity and downstream use. Always specify the format you want if you need structured data or easy-to-read lists.

Failing to provide clear formatting instructions can lead to inconsistent or hard-to-use responses. The AI might mix styles, omit important structure, or return information in a way that is difficult to process automatically. If you don't specify formatting, the AI may return information in an inconsistent or hard-to-use way.

The concept of a structured prompt is central to formatting control. A structured prompt includes explicit instructions about the format or structure of the desired output, ensuring that the AI's response matches your expectations.

Closely related is the idea of formatting control, which is the practice of guiding the AI to use a specific output style, such as Markdown, JSON, or numbered lists. This control is what makes structured prompts so effective and reliable for both human and automated use.