AI Fundamentals

Prompt Engineering

Last updated: February 16, 2026

Prompt engineering is the practice of crafting input text (prompts) to guide a large language model toward producing accurate, relevant, and useful outputs. It sits at the intersection of writing skill and technical understanding, requiring knowledge of how LLMs interpret and respond to different instruction styles.

How It Works

An LLM generates output based on the statistical patterns it learned during training, conditioned on the input you provide. Prompt engineering exploits this by structuring inputs to activate the most useful patterns. Common techniques include:

  • System prompts: Setting the model's persona, constraints, and output format before the user's message.
  • Few-shot examples: Providing sample input-output pairs so the model learns the desired pattern in context.
  • Chain-of-thought: Asking the model to reason step by step before giving a final answer, which improves accuracy on complex tasks.
  • Role assignment: Instructing the model to act as a specific expert (e.g., "You are a senior DevOps engineer").

Why It Matters

The same LLM can produce wildly different results depending on how you prompt it. Effective prompt engineering can mean the difference between a vague, unhelpful response and a precise, actionable one -- without changing the underlying model or incurring additional fine-tuning costs.

In Practice

When configuring an AI agent for deployment, the system prompt is one of the most impactful settings you control. It defines the agent's behavior, tone, capabilities, and boundaries. Well-engineered prompts also manage the context window efficiently by including only the most relevant instructions and context, reducing token usage and keeping responses focused. Iterating on prompts through testing and observation is a core part of building production-quality AI assistants.