Claude Code Basics — Aula 1: What is Claude Code and Installation

Welcome to Claude Code Basics

What if you could code three times faster, every single day? That’s not a marketing promise—it’s what developers using Claude Code are reporting right now.

In this lesson, you’ll discover what Claude Code actually is, see the measurable impact on real development teams, install it on your system, and run your first conversation. By the end, you’ll understand why CLI-based AI coding tools are rapidly replacing traditional IDE extensions.

What is Claude Code?

Forget everything you know about AI coding assistants. Claude Code doesn’t live in a chat window. It lives in your terminal, right next to your code.

Where Claude Code Actually Lives

Claude Code is Anthropic’s official CLI (Command Line Interface) tool. It reads your files, searches your patterns, and proposes code changes directly within your project.

This is fundamentally different from other AI coding assistants:

Anthropic’s official CLI tool that works directly in the terminal. Reads files, searches patterns, proposes changes. No monthly fee—just an API key.

Best for: Developers who prefer terminal workflows, want direct file access, and need full control over AI actions.

IDE-based AI coding assistant with agent capabilities, code review, and MCP integration. Works inside VS Code.

Best for: Developers who prefer GUI-based coding environments and want tight IDE integration.

Microsoft’s AI pair programmer integrated into GitHub and VS Code. Autocomplete-focused with chat features.

Best for: Enterprise teams already using GitHub and Visual Studio Code.

Real Teams, Real Impact

Development Teams
Teams report the impact as equivalent to having a senior developer available around the clock. Files get read, patterns get found, and changes get proposed without switching windows.

Privacy-Conscious Developers
Using self-hosted tools like Khoj as an AI second brain alongside Claude Code gives complete data control. Khoj has accumulated 33,983 GitHub stars from developers who need offline, private AI capabilities.

ML Researchers
Automated ML experiments using Claude Code through specialized templates, enabling rapid iteration on machine learning pipelines.

Job Seekers
Built an AI-powered job search system on Claude Code with 14 skill modes, PDF generation, and batch processing—this project earned 29,087 GitHub stars.

Email Marketing Professionals
Built a 55K-word specialized knowledge base and Claude Code skill for domain-specific expertise, demonstrating how Claude Code can be extended for any field.

Installing Claude Code

Installation takes under five minutes. The method depends on your operating system.

Installing Claude Code on Mac

If you have Homebrew installed, installation is a single command:

brew install claude-code

Installing Claude Code on Windows

You’ll use npm, the Node.js package manager. Make sure you have Node installed first.

npm install -g @anthropic-ai/claude-code

Installing Claude Code on Linux

The same npm command works on Linux:

npm install -g @anthropic-ai/claude-code

Configure Your API Key

After installation, you need to configure your Anthropic API key. Run claude in your terminal and follow the prompts:

claude

Claude Code requires an Anthropic API key to function. You can get one from the Anthropic Console. Keep your API key secure and never share it publicly.

Your First Conversation with Claude Code

What if Claude could instantly understand your entire project? Let’s make that happen.

Open your terminal and run claude. Type your first question and watch what happens:

What files are in this project?

Paste this prompt into Claude Code to get a detailed explanation of any file in your project.

How Claude Code Decides Which Tool to Use

When you ask Claude Code to fix a bug, it decides whether to read, grep, or run bash based on your request. Understanding this helps you phrase questions more effectively.

Claude Code has four main internal tools that work together seamlessly:

Read — Reads files from your project. Claude Code can read specific files, directories, or glob patterns.

Edit — Modifies code. Claude Code can make targeted changes to files, add new functions, or refactor existing code.

Bash — Executes terminal commands. Run tests, git commands, build scripts, or any shell command directly.

Web — Searches the web for documentation, Stack Overflow answers, or API references when local knowledge isn’t sufficient.

Three Permission Modes

Claude Code operates with a flexible permission system:

Search and Discovery Tools

Beyond the core tools, Claude Code includes powerful search capabilities:

• Grep — Search for patterns across your entire codebase
• Glob — Find files by name patterns
• Read directory — Understand your project structure

Tools Ecosystem

The Claude Code ecosystem extends far beyond the core CLI. Here are essential tools that integrate with or complement Claude Code:

Knowledge Check

Key Takeaways

What You’ve Learned:

1. Claude Code is a CLI tool — It lives in your terminal, not an IDE or browser, giving you direct access to your entire codebase
2. It’s free with an API key — No monthly subscription required, just an Anthropic API key
3. Three tools that work together — Read, Edit, and Bash combine for seamless code exploration and modification
4. Permission modes protect you — Auto-accept, Ask, and Deny give you control over what Claude Code can do
5. Rich ecosystem exists — Community tools like Awesome Claude Skills extend Claude Code for specialized workflows

Ready to Navigate Your Codebase?

You now have everything you need to install and start using Claude Code. The installation takes under five minutes, and your first conversation can happen immediately.

Next Lesson Preview: In Lesson 2, you’ll learn how to craft effective prompts that get the most out of Claude Code’s capabilities. We’ll cover prompt anatomy, context strategies, and how to ask questions that yield actionable code changes.