What is Claude Code? How to Use the New AI CLI for Coding

Claude Code is a command-line interface (CLI—a text-based tool for interacting with computer programs) that allows developers to write, debug, and manage code directly from their terminal using AI. By leveraging the Claude Opus 4.5 model, it can automate complex tasks like fixing bugs or refactoring entire files in under 60 seconds. This tool bridges the gap between your local development environment and AI, enabling you to build software through simple natural language commands.

How does Claude Code change your workflow?

Traditional AI coding often requires you to copy and paste code between your editor and a web browser. Claude Code eliminates this friction by living directly inside your terminal (the window where you run commands like git or npm). It has the power to read your local files, run tests, and even execute terminal commands to see if the code it wrote actually works.

Because it operates on your local machine, it understands the context of your entire project. It doesn't just look at one file; it can see how your different components interact across your whole folder structure. This makes it much more effective at solving "spaghetti code" issues or finding hidden bugs that span multiple files.

What do you need to get started?

Before you can use this tool, you need a few basic things set up on your computer. Don't worry if you haven't used the terminal much before; these tools are standard for almost all modern web development.

• Node.js version 22 or higher (recommended for best compatibility; minimum requirement is Node.js 18+): This is a runtime environment that lets you run JavaScript on your computer.
• An Anthropic API Key: This is a unique password that allows the tool to talk to Claude's "brain."
• A Terminal: On Mac, this is called Terminal or iTerm2; on Windows, you should use PowerShell or WSL (Windows Subsystem for Linux).
• Git: A version control system (a tool that tracks changes to your code) is highly recommended so you can undo any changes the AI makes.

How do you install and set it up?

Setting up Claude Code takes about five minutes if you have the prerequisites ready. Follow these steps to get your environment configured.

Step 1: Install the package Open your terminal and type the following command to install the tool globally on your system.

# npm is the package manager that comes with Node.js
npm install -g @anthropic-ai/claude-code

Step 2: Authenticate your account You need to link the tool to your Anthropic account so it can process your requests.

# This command starts the login process
claude login

Step 3: Navigate to your project Use the cd (change directory) command to go into the folder where your code lives.

# Replace 'my-web-app' with your actual folder name
cd my-web-app

Step 4: Launch the interface Simply type the name of the tool to start a session.

# This opens the interactive Claude Code prompt
claude

What you should see: Your terminal prompt will change, indicating that Claude is now listening for your instructions within that specific folder.

How do you give instructions to the AI?

Once the tool is running, you can talk to it just like you would a human colleague. It understands natural language, so you don't need to learn a new programming syntax to use it.

If you want to fix a specific bug, you might say: "Find why the login button isn't working in auth.js and fix it." Claude will read the file, identify the error, and ask for your permission to save the corrected version.

You can also ask it to explain complex parts of a codebase you didn't write. For example, typing "Explain how the data flows from the API to the dashboard" will prompt Claude to trace the logic through your files and give you a summary. We've found that using specific file names in your prompts helps the AI work faster and more accurately.

What are the common gotchas?

It is normal to feel a bit nervous when an AI starts editing your files. One common mistake is running Claude Code in a folder that isn't tracked by Git. If the AI makes a mistake and you aren't using version control, it can be difficult to revert those changes.

Another issue beginners face is "context window" limits. Even though Claude Opus 4.5 is powerful, asking it to "rewrite the whole app" at once can lead to errors or high costs. It is much better to give small, incremental tasks like "Add a search bar to the header" rather than massive, vague requests.

Finally, remember that the AI can execute terminal commands. If it suggests running a command you don't recognize, take a moment to read its explanation. It will always ask for your "Y/N" permission before doing anything major, so don't just mindlessly hit the Enter key.

How do you stay safe while using it?

Safety is a priority when giving an AI access to your computer's file system. Claude Code includes a "Permission System" that acts as a safety net for your work. Every time the AI wants to write to a file or run a command, it will display a clear summary of what it intends to do.

You should always review the "diff" (a view showing exactly which lines are being added or removed). This is your chance to catch logic errors before they become part of your project. If you are unsure about a change, you can simply type "No" or ask Claude to explain its reasoning.

In our experience, the best way to stay safe is to work on a separate "branch" (a parallel version of your code) in Git. This way, even if the AI makes a major mistake, your main project remains untouched and functional. You can experiment freely without the fear of breaking your production environment.

Next Steps

Now that you have the basics down, the best way to learn is by doing. Start by asking Claude to write a simple "ReadMe" file for one of your projects or have it add comments to a script you wrote a long time ago. As you get more comfortable, you can move on to automated testing and complex refactoring.

If you want to dive deeper into the specific flags and advanced configurations available, you should look at the official documentation. It provides detailed lists of every command the CLI supports.

For more information, visit the official Claude documentation.