# Claude Code tutorial: what it is, install and first steps

> A Claude Code tutorial for beginners: what it is, how to install it, the agent loop it runs and five things to try first. One command to install, no API key needed.

Source: https://devaiper.com/blog/what-is-claude-code
Published: 2026-10-08
Topics: Claude Code, Agents, Tutorial

**Short answer:** Claude Code is an AI coding agent you run in your terminal (or IDE). It reads your project, edits files, runs commands and tests, and asks before risky steps. Install it with one command, run claude in your repo and describe the task.

This Claude Code tutorial covers what it is, how to install it and what to do first. Autocomplete finishes the line you are typing. **Claude Code** takes the whole task: "add input validation to the signup form and update the tests". It reads the repo, edits several files, runs the tests, reads the failure, fixes it and shows you the diff.

## What Claude Code actually is

It is a coding **agent**: a language model running in a loop with tools. You give it a goal. It decides which tool to use next (read a file, search, edit, run a command), looks at the result, and repeats until it is done or needs you.

> **Diagram:** The Claude Code loop. Gather context by reading and searching, take action by editing files and running commands, then verify with tests and diffs, and repeat until the task is done.
> Gather context (read files, search, git log) → ... → Take action (edit files, run commands) → ... → Verify (run tests, check the diff)
> The agent loop. You stay in it: approve actions, redirect, or stop.

The important word is **verify**. An agent that can run your tests is far more useful than one that only writes code, because it can find out it was wrong.

## Install it

The official docs recommend the native installer. It updates itself in the background.

```bash
# macOS, Linux, WSL
curl -fsSL https://claude.ai/install.sh | bash
```

```powershell
# Windows PowerShell
irm https://claude.ai/install.ps1 | iex
```

Homebrew (`brew install --cask claude-code`) and WinGet also work, but they do not auto-update, so you upgrade them yourself. Open a new terminal and check:

```bash
claude --version
```

## Start your first session

```bash
cd /path/to/your/project
claude
```

On first use it asks you to sign in. A Claude subscription (Pro, Max, Team or Enterprise), a Claude Console account, or a supported cloud provider all work. You do not need to paste files in: Claude Code reads what it needs.

## Five things to try first

1. **Explore:** `what does this project do?` then `where is the main entry point?`
2. **A small change:** `add a hello world function to the main file`. Approve the edit when it asks.
3. **A real bug:** `users can submit the empty form. Fix it and add a test.`
4. **Git:** `what files have I changed?` then `commit my changes with a descriptive message`.
5. **A refactor:** `refactor the auth module to use async/await, run the tests after each file`.

## Commands you will use daily

| Command | What it does |
|---|---|
| `claude` | Start an interactive session |
| `claude "task"` | Start with a first prompt |
| `claude -p "query"` | Run once and print the answer (good for scripts) |
| `claude -c` | Continue the most recent conversation |
| `claude -r` | Pick a previous conversation to resume |
| `/clear` | Wipe the conversation context |
| `/help` | List commands |
| `Shift+Tab` | Cycle permission modes |

## Permissions: what it can do without asking

By default it asks before editing files or running commands. The session's permission mode controls how much it can do on its own, and `Shift+Tab` switches modes. Start strict, loosen it only for tasks you trust, and read every diff before you commit. If something must never happen, enforce it with a hook rather than hoping the instructions are followed.

## How to get good results

- **Be specific.** "Fix the login bug where users see a blank screen after entering wrong credentials" beats "fix the bug".
- **Let it explore first.** Ask it to analyze before you ask it to change.
- **Give it a way to check itself.** Tests, a linter, a type check. Tell it the command.
- **Write down what you keep repeating.** Put it in a [CLAUDE.md file](https://devaiper.com/blog/claude-md-guide).
- **Keep tasks small and verifiable.** This is delegation: if you cannot tell when it went wrong, keep your hands on it. See the [4D framework](https://devaiper.com/blog/4d-framework-ai-fluency).

## When Claude Code is the wrong tool

If you need a one-line answer, a chat is faster. If you cannot review the diff, do not let an agent make it. And if the whole goal is to avoid understanding the code, read [vibe coding vs AI-assisted engineering](https://devaiper.com/blog/vibe-coding-vs-ai-assisted-engineering) first.

Official quickstart: [code.claude.com/docs/en/quickstart](https://code.claude.com/docs/en/quickstart).

## FAQ

### What is Claude Code?

Claude Code is an AI coding agent. You run it in a project directory, describe a task in plain language, and it reads files, edits code, runs commands and tests, and shows you what it changed.

### How do I install Claude Code?

On macOS, Linux or WSL run curl -fsSL https://claude.ai/install.sh | bash. On Windows PowerShell run irm https://claude.ai/install.ps1 | iex. Homebrew (brew install --cask claude-code) and WinGet also work. Then run claude --version to check.

### Do I need an API key to use Claude Code?

No. You can sign in with a Claude subscription (Pro, Max, Team or Enterprise) or a Claude Console account, or use a supported cloud provider. If ANTHROPIC_API_KEY is set and you approve it, Claude Code uses that key.

### Is Claude Code only for the terminal?

No. It also runs in VS Code and JetBrains IDEs, as a desktop app, on the web, in Slack and in CI through GitHub Actions and GitLab. The terminal version is the most complete.

### How is Claude Code different from autocomplete tools?

Autocomplete suggests the next lines while you type. Claude Code is an agent: it plans a task, uses tools across many files, runs your tests, reads the failures and keeps going until the task is done or it needs your decision.