Talking to Claude: The Basics

Every conversation with Claude begins with a message from you — a “prompt”. This course teaches one skill: writing prompts that get exactly the answer you want. But first, let’s see how a conversation with Claude actually works behind the scenes.

Three dials behind every conversation

When programmers connect to Claude, every message travels with a few settings. In a normal chat window these are already set for you — but knowing they exist helps you understand Claude’s behavior:

The model — which version of Claude answers you. Bigger models are smarter; smaller ones are faster and cheaper.
The answer-length limit — a hard ceiling on how long the reply may be. Set too low, the answer gets cut off mid-sentence.
The “temperature” — how much variety Claude is allowed. At zero, the same question gives nearly the same answer every time; higher values give more creative, varied answers.

The turn-taking rule

A conversation with Claude is strict turn-taking, like a game of tennis: you speak, Claude speaks, you speak, Claude speaks — and it must always start with you. Programmers who break this rule (say, by sending two user messages in a row with no reply between them) simply get an error back. In a chat window you can never break it, because the window manages the turns for you.

Hidden inside this rule is a powerful trick: it is possible to write the beginning of Claude’s own reply yourself, and let Claude continue from where you left off. Chapter 5 shows what this trick can do.

A normal conversation

Nothing special is needed for everyday questions — a correctly formed message simply gets a helpful answer:

YOU WRITE

Hi Claude, how are you?

CLAUDE ANSWERS

I’m doing well, thank you! How can I help you today?

YOU WRITE

Can you tell me the color of the ocean?

CLAUDE ANSWERS

The ocean usually appears blue, but the color varies — it can look green, gray, or turquoise depending on depth, weather, and what’s in the water.

YOU WRITE

What year was Allama Iqbal born in?

CLAUDE ANSWERS

Allama Muhammad Iqbal was born on November 9, 1877, in Sialkot.

The system prompt — a briefing before the meeting

There is one more piece: the system prompt. It is a set of standing instructions given to Claude before the conversation begins. Think of it as a briefing memo handed to a new employee before their first meeting: the customer never sees the memo, but it shapes how the employee behaves all day.

The system prompt is the best place for rules, background, and “how to behave” instructions. Watch what happens when a system prompt quietly changes the whole game:

STANDING INSTRUCTION (SYSTEM PROMPT)

Always answer with critical-thinking questions that push the conversation deeper. Never give the actual answer.

YOU WRITE

Why is the sky blue?

CLAUDE ANSWERS

Interesting question! What do you think happens when sunlight enters the atmosphere? Why might some colors of light behave differently than others? What have you noticed about the sky’s color at sunset compared to midday?

Claude never answered the question — because the standing instruction told it not to. That is the quiet power of a system prompt: it controls every reply without ever appearing in the conversation.

REMEMBER

A prompt is just your message. Conversations take strict turns and always start with you. And the system prompt is a hidden briefing that shapes every answer — the best home for your standing rules.