What Is Claude Code? The AI Agent That Actually Executes

Claude Code isn't a chatbot you copy-paste from. It's an AI agent that runs in your terminal, accesses your files, and does real work on your computer.

Claude Code is an AI agent by Anthropic that runs in your terminal (and in VS Code and JetBrains) and actually executes tasks on your computer -- reading files, writing code, running commands, and building projects. Unlike chatbots where you copy-paste suggestions, Claude Code operates directly on your real files and keeps working until the job is done.

With the February 2026 release of Claude Opus 4.6, it can now coordinate agent teams to tackle larger projects with multiple parallel workstreams. As Lenny Rachitsky put it: "Forget it's called Claude Code. Think of it as Claude Local or Claude Agent. It's a super-intelligent AI running locally, able to do anything on your computer."

How Claude Code Actually Works

Claude Code operates in an agentic loop. You describe what you want, and Claude:

1. Reads your files to understand context
2. Creates a plan for how to accomplish the task
3. Executes the plan by writing code, running commands, and modifying files
4. Observes the results (including errors)
5. Iterates until the task is complete

This isn't copy-paste AI. It's an agent that operates on your actual files, sees the results, and keeps working until it's done.

The Context Window

Claude Code has a context window—a limited amount of information it can hold at once. Every file it reads, every command output, every message fills this window. With Claude Opus 4.6, the context window extends to 1 million tokens (in beta), and context compaction automatically summarizes older context so longer-running tasks don't hit limits.

Understanding context is still crucial because performance degrades at around 30% capacity, not 100%. When context fills up, Claude starts making more mistakes. This is why power users frequently use /clear between tasks and /compact to compress context.

The Three Modes

Claude Code operates in three modes. Press Shift + Tab to cycle between them:

Plan Mode is particularly powerful. It separates research from execution—Claude reads files, understands your project, and creates a detailed plan before writing any code. Boris Cherny, Claude Code's creator, says: "A good plan is really important!"

Key Features That Make Claude Code Different

1. CLAUDE.md: Persistent Project Memory

CLAUDE.md is a special file that Claude reads at the start of every session. It's your project's constitution—permanent context that doesn't need to be re-explained.

Run /init to generate a starter file, then customize it:

# Project Context

## What this project does
A marketing automation tool for B2B SaaS companies.

## Tech stack
- Next.js frontend
- Python backend
- PostgreSQL database

## Commands
- Run tests: npm test
- Start dev: npm run dev
- Deploy: npm run deploy

## Code style
- Use TypeScript, not JavaScript
- Prefer functional components
- No inline styles

Keep it under 300 lines. Claude reads it every session, so make every line count.

2. Slash Commands

Built-in commands that change how Claude works:

3. Skills and Custom Commands

Skills are reusable workflows that Claude remembers. Create a file at .claude/skills/my-workflow/SKILL.md:

---
name: content-audit
description: Analyze content library and find gaps
---

When running a content audit:
1. Read all markdown files in /content
2. Categorize by topic and date
3. Find gaps in coverage
4. Create HTML report with recommendations

Custom commands store frequently-used prompts. Create .claude/commands/my-command.md and it becomes available as /project:my-command.

4. Subagents and Agent Teams

Claude can delegate tasks to subagents—specialized AI instances that run in separate context windows. This keeps your main conversation clean while investigating complex problems.

"Use a subagent to review this code for security issues."
"Have a subagent investigate why the tests are failing."

Subagents can be configured with custom prompts, tool restrictions, permission modes, hooks, skills, and even their own MCP servers. You can specify which model a subagent uses, set a maximum number of turns, and restrict which tools it can access.

With Claude Opus 4.6 (released February 2026), this expands into full agent teams — groups of agents that can split larger tasks into segmented jobs and work on them in parallel. This makes it possible to tackle bigger projects that would have overwhelmed a single agent.

5. Hooks

Hooks are user-defined shell commands that execute at specific points in Claude Code's workflow. Unlike skills (which Claude may or may not choose to use), hooks are deterministic — they always run when triggered.

Three hook types:

• PreToolUse — Runs before Claude executes a tool. Can block or modify actions (e.g., prevent writes to certain directories).
• PostToolUse — Runs after a tool completes. Great for auto-formatting code, running linters, or enforcing style guides.
• Notification — Fires when Claude needs your attention. Can send Slack messages or desktop notifications when a task finishes.

6. MCP (Model Context Protocol)

Connect Claude Code to external tools via MCP servers:

• Databases (PostgreSQL, MongoDB)
• APIs (GitHub, Notion, Slack)
• Browser automation
• File systems

Run claude mcp add to connect new tools. MCP servers can also be configured for subagents, giving them access to external data sources while keeping your main session clean.

7. IDE Integration

While Claude Code started as a terminal-only tool, it now integrates with popular IDEs:

• VS Code: Official extension with native GUI, diff viewers, multi-tab conversations, and @-mention files with line ranges
• JetBrains IDEs: Beta plugin that runs the CLI inside your IDE terminal with built-in diff review

Both integrations use the same underlying Claude Code installation. The terminal remains the most full-featured interface, but IDE integration lowers the barrier for users who prefer a graphical environment.

Claude Code vs ChatGPT: Key Differences

The fundamental difference: ChatGPT is a conversation partner. Claude Code is a work partner.

What Claude Code Is Good At

File Operations

Renaming, organizing, converting, processing. Anything you'd normally do with a script or manual tedium.

Code Generation and Editing

Build full applications, add features to existing projects, refactor code, write tests. It works in your actual codebase, not hypothetical examples.

Automation

Data pipelines, report generation, content processing, API integrations. Describe the workflow, and it builds it.

Research and Analysis

Web scraping, data extraction, document summarization, competitive research. It gathers and organizes information from various sources.

What Claude Code Is NOT

• Not a chatbot — It's a tool for getting work done, not having conversations
• Not magic — It makes mistakes, especially on complex tasks. You still review its work.
• Not a replacement for understanding — If you don't understand what it's building, you'll struggle to maintain it
• Not free — Requires Claude Pro ($20/mo), Max ($100-200/mo), Team ($25-150/mo per seat), Enterprise (custom), or API credits

Who Is Claude Code For?

The sweet spot is people who have ideas but hit technical walls:

• Marketers who want to automate reports, scrape competitor data, or build internal tools
• Data analysts who know what they want but struggle with the code to get there
• Content creators who want to build systems instead of doing everything manually
• Business owners who need custom solutions but can't justify hiring a developer
• Developers who want to move faster on routine tasks

If you can clearly describe what you want, Claude Code can often build it.

Want to see it in action? Get the CAIO Blueprint using only plain English — no coding, no setup tutorials, just results.

The Learning Curve

There is a learning curve, but not because Claude Code is complicated. The learning curve is in thinking clearly about what you want and understanding how to use context effectively.

The key concepts to master:

1. Context management — Use /clear between tasks, /compact when running low
2. CLAUDE.md setup — Invest time in creating good project memory
3. Plan Mode — Research before execution on complex tasks
4. Verification — Always give Claude a way to check its own work

Getting Started

If you want to try Claude Code:

1. Mac, Linux, or Windows — Windows now works natively without WSL
2. Get Claude access via Claude Pro/Max subscription or API key
3. Install Claude Code using the native installer (no Node.js required):
   Mac/Linux: curl -fsSL https://claude.ai/install.sh | bash
   Windows: irm https://claude.ai/install.ps1 | iex
4. Launch: type claude in your terminal
5. Set up project memory: run /init in your project folder

For a detailed walkthrough, see our installation guide.

The Bottom Line

Claude Code represents a shift from AI as a consultant that gives advice to AI as an agent that takes action.

It's not perfect. It makes mistakes. Complex projects still require oversight. But for the right use cases — automating tedious work, building simple tools, processing files, generating content — it can save hours of manual effort.

The question isn't whether AI can help you work faster. It's whether you're willing to learn a new way of working.

The Latest: Claude Opus 4.6 (February 2026)

Claude Code is powered by Anthropic's Claude models, and the latest is Claude Opus 4.6, released February 5, 2026. Key improvements for Claude Code users:

• 1M token context window (beta) — work with much larger codebases without running out of context
• Agent teams — multiple agents splitting larger tasks into parallel workstreams
• Context compaction — automatic summarization of older context for longer-running tasks
• 128K token output — Claude can complete larger tasks without breaking them into multiple requests
• Better coding performance — improved planning, longer sustained agentic tasks, better code review and debugging

You can switch between models in Claude Code using the /model command. The default model depends on your subscription tier. Other available models include Claude Sonnet 4.5 (faster, lower cost) and Claude Haiku 4.5 (fastest, lowest cost).

Related Guides

• How to Install Claude Code — step-by-step setup for Mac, Windows, Linux
• Claude Code Tutorial for Beginners — build your first project
• 25 Claude Code Prompts — copy-paste examples that work
• Claude Code vs ChatGPT — understand the key differences
• Claude Code vs Cursor — which tool should you use?
• Claude Code Pricing — complete cost breakdown
• Claude Code for Non-Coders — you don't need to be a programmer