Prompt

A prompt is whatever you send a generative model: “Summarize this contract”, a photo with “what’s wrong with my plant?”, or pages of background material followed by a question. The model’s reply is called the completion or output.

Types of prompts

• User prompt: what you type or upload.
• System prompt: hidden instructions set by the app developer that shape the model’s role, tone and rules (“You are a helpful customer-service assistant for…”).
• Few-shot prompt: includes worked examples so the model copies the pattern.

Prompts and cost

Everything in the prompt counts toward the model’s context window and is billed as input tokens. Many APIs offer discounted prompt caching when the same long prompt is reused.

Prompt security

Because models follow instructions in their input, malicious text hidden in a web page or document can try to hijack them. This is called prompt injection, and it is a major security concern for SI agents that read untrusted content.

Learn how to write better prompts in prompt engineering.