System Prompt
intermediateDefinition
A set of background instructions you give an AI before the actual conversation starts. It defines the AI's role, personality, and any rules it should always follow: like a job description it never forgets, no matter what the user asks next.
In the wild
Before a customer service chatbot answers anyone, it's given a system prompt: 'You are a friendly support agent for a shoe company. Always be polite, never make up a refund policy, and ask for an order number when you need one.' Every customer chat then follows those rules.
More from AI & Prompt Engineering
Agentic AI
An AI that can do more than answer one question at a time. You give it a goal, and it figures out the steps, takes them, checks the results, and keeps going until the job is done: without you holding its hand at each step.
Chain of Thought
A trick where you ask the AI to think out loud, walking through its reasoning step by step, before giving a final answer. It sounds simple, but it dramatically improves accuracy on math problems, puzzles, and anything that needs careful logic.
Context Files (CLAUDE.md, AGENTS.md)
Markdown files kept at the root of a repo that describe conventions, commands, and non-negotiables for an AI coding assistant. The assistant loads them automatically, so they're where you put the rules you don't want to repeat in every prompt.
Context Window
How much text an AI can hold in its head at once: both what you send it and what it writes back. A bigger context window means it can read longer documents, remember more of a conversation, or look at more files at the same time.
Few-Shot Prompting
Showing the AI a few examples of exactly what you want before asking it to do the same for your real input. The examples teach it the pattern far more reliably than a long description ever could.
Fine-Tuning
Taking an AI that already knows a lot and giving it extra training on a smaller, more focused set of examples. So it gets really good at one specific job or style. Unlike just writing a clever prompt, fine-tuning actually changes how the AI thinks.