claude-code-best-practice/tutorial/day0/Day0.md

Day 0 — Claude Code Setup

This guide walks you through installing Claude Code on your machine and authenticating so you can start using it.

Step 1: Install Claude Code

Choose your operating system:

OS	Guide
Windows	windows.md
Linux	linux.md
macOS	mac.md

Follow the guide for your OS, then come back here for authentication.

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Step 2: Verify Installation

After following your OS-specific guide, confirm everything is working:

node --version    # Should show v18.x or higher
claude --version  # Should show the installed Claude Code version

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Step 3: Login

Run claude in your terminal. On first launch, it will ask you to choose a login method.

Method 1: Subscription (Claude Pro / Max)

• Select Claude.ai account
• Browser opens — sign in and authorize
• Return to terminal, you're logged in

Method 2: API Key (Pay-as-you-go)

• Go to console.anthropic.com → API Keys → Create Key
• Select Anthropic API Key in the prompt
• Paste your key (starts with sk-ant-)

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