Claude Code Basics

Claude Code is Anthropic's agentic coding tool, built for developers who want to delegate coding tasks directly from their command line, desktop app, or mobile app rather than manually writing every line themselves.

Installation and setup. Claude Code is typically installed via a package manager and run from a terminal inside a project directory. Once running, it can read your project's files, understand its structure, and make changes directly — writing code, running tests, and executing commands on your behalf.

Core interaction model. Unlike a simple chat interface, Claude Code is agentic: you give it a task in natural language, and it plans and executes the steps needed to complete it, which may include reading multiple files, running terminal commands, writing new code, and verifying its own work — often across many steps without needing you to manually direct each one.

Where it fits. Claude Code is designed for real, hands-on software work: building features, fixing bugs, writing tests, refactoring code, and more. It's distinct from asking a general chat assistant for code snippets, since it can actually execute changes in your real project and iterate based on results (like test failures or build errors) rather than just producing text for you to copy and paste.

Access points. Beyond the terminal, Claude Code is also available inside popular code editors and as a desktop app, and can be accessed remotely through the Claude mobile app — letting developers kick off or check on tasks away from their main machine.

A typical session. A developer might describe a feature in a sentence or two, and Claude Code will explore the relevant parts of the codebase, propose or make the necessary changes across however many files are involved, run the project's existing tests to check its work, and report back what it did — closer to delegating a task to a colleague than to querying a search engine.

Permissions and control. Because Claude Code can modify files and run commands in a real project, it operates under a permission model: actions that change things ask for approval, and you can grant broader standing permissions for operations you trust as you get comfortable. This keeps the developer in charge of what actually happens to the codebase — you can watch every step, approve categories of actions in advance, or run more autonomously once a workflow has earned trust. Reviewing the diff of what changed, exactly as you would review a teammate's pull request, remains the fundamental habit.

Project instructions. Claude Code reads instruction files checked into a project — conventions, build commands, architectural notes, things to avoid — and applies them across sessions. Teams use these files to encode how their project works: which package manager to use, how tests are run, what style rules apply, and which parts of the codebase deserve special care. A few well-maintained lines of project instructions noticeably improve the consistency of everything the tool does in that repository, because it stops rediscovering (or guessing at) the same conventions every session.

Working with tests and builds. One of the most practical differences between an agentic tool and a snippet generator is the feedback loop. Claude Code can run the project's test suite, read failures, and revise its changes in response — repeating until tests pass or reporting honestly when something remains unresolved. The same applies to compilers, linters, and formatters: the tool's output is shaped by the project's actual quality gates, not just by what looks plausible in isolation.

What it is not. Claude Code does not replace code review, testing discipline, or a developer's judgment about design. Generated changes can be wrong in subtle ways, and responsibility for what ships stays with the humans on the team. Treating its output the way you would treat a capable new teammate's — trusted to do real work, always reviewed before merging — is the mental model that experienced users converge on.

Getting started. The learning curve is gentler than it may appear. A good first session is a small, well-defined task on a project with existing tests: fix a specific bug, add a small feature, or write tests for one module. Clear instructions, a scoped task, and a look at the resulting diff will teach you more about how the tool operates than any amount of reading. From there, tasks can grow in scope as your sense of what it handles well develops.

How it changes day-to-day work. Developers who adopt agentic tools tend to report a shift in where their time goes rather than a simple reduction in it: less time typing routine code and chasing mechanical errors, more time specifying what should be built, reviewing what came back, and making the design decisions the tool cannot make. The skills that grow in value are exactly the ones good engineers already have — describing problems precisely, reading diffs critically, and knowing what a correct solution looks like before accepting one. Understanding these fundamentals — what makes it agentic, how it differs from simple code generation, and where you'd reach for it — is the foundation for using Claude Code effectively on real projects.