Lesson 2 of 3•Advanced Prompt Engineering0 of 3 complete (0%)
System Prompts & Personas
10 min
What you will learn
- Write system prompts that control AI behavior, tone, and expertise across an entire conversation
- Create reusable personas for different tasks (analyst, editor, strategist, tutor)
- Understand the difference between system prompts and user prompts and when to use each
- Build a library of system prompts you can reuse across projects
# System Prompts & Personas
A system prompt sets the rules for an entire conversation. It tells the AI who it is, how to behave, and what constraints to follow — before any user messages arrive.
System Prompts vs. User Prompts
User prompt: What you type in the chat. Changes every message. System prompt: Background instructions that persist across the conversation. Set once.
Most AI interfaces let you set system prompts:
- Claude API: The system parameter
- ChatGPT: Custom Instructions or the system message
- Claude.ai Projects: Project instructions
- Any API integration: The first message with role "system"
Anatomy of a Great System Prompt
You are [ROLE] with expertise in [DOMAINS].
BEHAVIOR:
- [How to communicate: tone, length, style]
- [What to prioritize in responses]
- [What to avoid]Unlock this lesson
Upgrade to Pro to access the full content
What you'll learn:
- Write system prompts that control AI behavior, tone, and expertise across an entire conversation
- Create reusable personas for different tasks (analyst, editor, strategist, tutor)
- Understand the difference between system prompts and user prompts and when to use each