Imagine hiring an assistant who starts every conversation by reading your project notes — your brand colors, your rules, your preferences. That's what CLAUDE.md does. It's a file that lives in your project folder and teaches Claude about your specific project before you say a word.
No more repeating yourself. No more "I told you this already." You write the rules once, and Claude follows them every time you work together.
The Problem CLAUDE.md Solves
Without CLAUDE.md, every conversation starts from zero. Claude doesn't know your brand, your preferences, or your project structure. It makes reasonable guesses — but they're still guesses. With CLAUDE.md, Claude reads your rules before you even type your first message.
Same request. Completely different results. The only difference is that one project has a CLAUDE.md file and the other doesn't.
What Goes in CLAUDE.md
Think of CLAUDE.md as a short briefing document for a new team member. What would they need to know to start contributing without asking a dozen questions? Here are the key sections:
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Project Overview
What is this project? Who is it for? A sentence or two that gives Claude the big picture so it makes decisions that fit the context.
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Style Rules
Colors (with hex codes), fonts, border radius, spacing preferences. The visual DNA of your project so every page looks like it belongs.
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Do's and Don'ts
Explicit rules like "always use rounded corners" or "never use pop-up modals." These prevent Claude from making choices you'll have to undo.
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File Structure
Where things live in the project. Which folder holds images, which file is the home page, where stylesheets go. This keeps your project organized.
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Technical Choices
What tech stack you're using, which libraries to include, any conventions to follow. This stops Claude from introducing tools you don't want.
A Real Example
Here's what a CLAUDE.md looks like for a fictional coffee shop website. Notice how it's written in plain English — no code knowledge required. Just clear, specific instructions that anyone could write.
Thirty lines. That's all it takes. Every page Claude builds for this project will use cream backgrounds, espresso-colored text, Playfair Display headings, and rounded corners — automatically.
How Claude Uses It
When you open Claude Code inside a project folder, Claude automatically reads the CLAUDE.md file before you say anything. Every request you make after that inherits the context. You don't need to reference it or load it manually — it just works.
You asked for an events page. You didn't mention colors, fonts, corners, or navigation. Claude knew all of that because it read CLAUDE.md first. This is the power of persistent project context — you focus on what you want, and Claude handles the how based on your rules.
Building Up Over Time
CLAUDE.md isn't a one-time thing you write and forget. It's a living document that grows with your project. The best approach: start small and add rules as situations come up.
- When Claude makes a decision you like, add it to CLAUDE.md so it keeps doing it.
- When Claude makes a mistake, add a "don't" rule so it never happens again.
- When you add a new page or feature, update the file structure section.
Here's what that looks like in practice. Say Claude used a pop-up for the newsletter signup, and you hate pop-ups:
Now Claude will never use a popup on this project again. Your CLAUDE.md just got smarter.
Your CLAUDE.md doesn't need to be long. Even 10 lines of clear rules will dramatically improve consistency. Start small and grow it. A short, well-written CLAUDE.md beats a sprawling one that Claude has to parse through. Focus on the rules that matter most to you.
Create a CLAUDE.md for the recipe site you built in Lesson 4. Include:
- A project name and one-sentence description
- Your color palette (at least 3 colors with hex codes)
- Font preferences for headings and body text
- At least 2 "do" rules and 2 "don't" rules
Then ask Claude to add a new feature — like a "favorites" page or a search bar — and see if it follows your rules without being reminded.
Review Flashcards
Click each card to reveal the answer. Use the arrows to move between cards.
Fill in the Blank
The section tells Claude what the project is and who it's for.
You should include color values as so Claude uses the exact shades you want.
CLAUDE.md is a that grows and evolves as your project develops.
Key Takeaways
- CLAUDE.md is a context file that Claude reads automatically when you open a project folder. It gives Claude memory about your project.
- Include your project overview, style rules (colors, fonts), do's and don'ts, file structure, and technical choices.
- With CLAUDE.md, every request inherits your project's rules. You stop repeating yourself and Claude stays consistent.
- Start small — even 10 lines makes a difference. Add rules over time as Claude makes decisions you want to reinforce or prevent.
- CLAUDE.md is a living document. Update it when your project grows, when you add new rules, or when you discover a new "don't."