Anthropic’s Claude Code uses a .claude/ folder system to control AI behavior in development projects, according to a detailed breakdown published by Avi Chawla on Daily Dose of Data Science on March 23, 2026. The folder structure serves as what Chawla calls “the control center for how Claude behaves in your project,” containing instructions, custom commands, permission rules, and session memory.
The system actually uses two separate .claude directories rather than one. A project-level folder holds team configuration that gets committed to git, ensuring “everyone on the team gets the same rules, the same custom commands, the same permission policies.” Meanwhile, a global ~/.claude/ folder in the user’s home directory stores personal preferences and machine-local state, including session history and auto-memory.
The most critical component is the CLAUDE.md file, which Chawla describes as “Claude’s instruction manual.” When Claude Code starts a session, it loads this file directly into the system prompt and maintains it throughout the conversation. “Simply put: whatever you write in CLAUDE.md, Claude will follow,” Chawla writes. The system can read multiple CLAUDE.md files from different locations—project root, global directory, and subdirectories—and combines their instructions.
For optimal performance, Chawla recommends keeping CLAUDE.md files under 200 lines, noting that “files longer than that start eating too much context, and Claude’s instruction adherence actually drops.” The file should include build and test commands, architectural decisions, coding conventions, and project structure, while avoiding content that belongs in linter configs or lengthy theoretical explanations.
The configuration system allows development teams to standardize how Claude Code operates across projects and team members. By understanding the folder structure, teams can configure Claude Code to follow specific coding standards, use particular testing frameworks, and adhere to project-specific architectural patterns without manual instruction in each session.
