CLAUDE.md is a Markdown file used to configure and customize the behavior of Claude Code, an AI coding assistant. It acts as a persistent memory for Claude, providing it with project-specific instructions, coding standards, and other relevant information. Without a CLAUDE.md file, Claude starts each session from scratch, lacking context and knowledge of team conventions. By using CLAUDE.md, developers can ensure Claude aligns with the project vision and maintains consistency across sessions.
Anthropic is the creator of Claude and Claude Code. The CLAUDE.md file is automatically loaded by Claude Code at the start of each session. It is treated as an authoritative source of system rules, taking precedence over user prompts. A well-written CLAUDE.md file can significantly reduce manual corrections and improve Claude's ability to generate production-ready code. Key features include defining project architecture, coding style guidelines, and common commands. The file can be placed at the root of a project or in the user directory, and Claude Code recursively searches for CLAUDE.md files in multiple locations, merging their contexts.
Claude Code is available as part of the Claude Pro and Max plans. Claude's pricing tiers include a free plan, a Pro plan at around $20/month, and higher tiers at $100 to $200/month. The $100/month plan (Max 5x) is considered a sweet spot for serious users, while the $200/month (Max) plan is for heavy users. These plans provide access to Claude Code and other features, with varying usage limits. For high-volume usage, the API offers a pay-per-token model. Claude Opus 4.5, a more efficient model, is priced at $5/$25 per million tokens.
