What Is Claude Code?
Claude Code is an agentic AI coding tool built by Anthropic that lives entirely in your terminal. Unlike browser-based assistants or IDE extensions that offer line-by-line suggestions, Claude Code operates as a fully autonomous agent capable of understanding your entire codebase, executing multi-step plans, and making coordinated changes across dozens of files in a single conversation.
Think of it as having a senior engineer sitting next to you who can read every file in your project, run your tests, debug your errors, and commit changes — all through natural language conversation in your terminal.
How Claude Code Differs from Copilot and Cursor
If you have used GitHub Copilot or Cursor, you might wonder what makes Claude Code different. The distinction is fundamental: those tools primarily offer code completion (predicting the next few lines as you type), while Claude Code offers agentic coding (planning, executing, and verifying entire workflows).
| Feature | GitHub Copilot | Cursor | Claude Code |
|---|---|---|---|
| Interface | IDE inline suggestions | IDE with AI panel | Terminal-native |
| Interaction Model | Autocomplete / Chat | Chat + Composer | Agentic conversation |
| Context Window | ~8K-32K tokens | ~32K-128K tokens | Up to 1M tokens |
| File Editing | Single file focus | Multi-file with tab | Multi-file autonomous |
| Tool Execution | Limited | Moderate | Full (bash, grep, read, write) |
| Git Integration | Basic | Basic | Deep (commit, PR, diff analysis) |
| Autonomous Actions | No | Partial | Yes, with permission controls |
The most significant advantage is the 1 million token context window. This means Claude Code can hold your entire medium-sized codebase in memory simultaneously. It does not lose track of a file you discussed 30 minutes ago, and it can reason about how a change in one module affects another module hundreds of files away.
The Agentic Loop
At the heart of Claude Code is the agentic loop, a continuous cycle that powers every interaction:
- You speak — You describe what you want in natural language ("Add pagination to the blog index page").
- Claude plans — The agent analyzes your request, reads relevant files, and formulates a multi-step plan.
- Claude acts — It executes tools: reading files, searching code, editing files, running terminal commands.
- Claude observes — It examines the results of each action (compiler output, test results, file contents).
- Claude decides — Based on observations, it either continues with the next step, adjusts its approach, or reports completion.
This loop runs continuously until the task is complete. A single prompt from you might trigger dozens of tool calls — reading 15 files, editing 4, running tests, fixing a failing test, and running tests again — all without further input from you.
# A single prompt can trigger a complex agentic workflow
$ claude
> Add rate limiting middleware to all API routes, write tests, and update the README
# Claude will autonomously:
# 1. Read your route files to understand the API structure
# 2. Check existing middleware for patterns
# 3. Create the rate limiting middleware
# 4. Register it in the appropriate configuration
# 5. Apply it to API route groups
# 6. Write feature tests
# 7. Run the tests to verify they pass
# 8. Update README documentation
Why Terminal-First Design Matters
Claude Code runs in your terminal by design, not as a compromise. The terminal is where professional developers already spend significant time — running builds, managing git, debugging deployments, and orchestrating infrastructure. By living in the terminal, Claude Code gains direct access to your entire development environment:
- Shell access — It can run any command you can run: build tools, test suites, linters, database clients, Docker, kubectl, and more.
- No context switching — You stay in one environment instead of bouncing between an IDE panel and a terminal.
- Composability — You can pipe output to Claude, use it in shell scripts, or chain it with other CLI tools.
- SSH and remote work — It works seamlessly on remote servers, containers, and CI environments where a GUI is not available.
# Pipe output directly to Claude for analysis
$ cat error.log | claude "What's causing these 500 errors?"
# Use Claude in non-interactive scripts
$ claude -p "Generate a migration for adding a 'verified_at' column to users table" --output-file migration.php
Who This Course Is For
This course is designed for working developers who want to dramatically accelerate their productivity. Whether you are a solo freelancer, a startup engineer, or part of a large team, Claude Code adapts to your workflow. You do not need prior experience with AI coding tools, but you should be comfortable with the command line and have at least basic programming experience.
Key Takeaways
- Claude Code is an agentic AI tool that operates autonomously in your terminal, going far beyond simple code completion
- The agentic loop (speak → plan → act → observe → decide) allows Claude to execute complex, multi-step tasks from a single prompt
- A 1 million token context window means Claude Code can reason about your entire codebase simultaneously
- Terminal-first design provides direct access to your full development environment — shell commands, git, build tools, and more
- Claude Code is fundamentally different from Copilot and Cursor in its ability to plan and execute entire workflows autonomously