What is Cursor AI Editor?

Cursor is an AI-powered code editor built on VS Code with Claude 4.5 Sonnet integration. It features Tab completion for 30-50% faster coding, Cmd+K for surgical edits, AI Chat (Cmd+L) for questions and debugging, and Composer for multi-file editing.

How do I use Tab completion in Cursor?

Tab completion in Cursor predicts 1-15 lines of code. Start typing a function name or code pattern, and press Tab to accept the AI suggestion. Use Cmd+→ to accept word-by-word, and Alt+[ or Alt+] to cycle through alternatives.

What is Cmd+K in Cursor?

Cmd+K (Ctrl+K on Windows/Linux) is Cursor's inline editing feature. Select code, press Cmd+K, describe your change in plain English (like 'add error handling' or 'convert to TypeScript'), and Cursor makes the edit instantly.

How do @ symbols work in Cursor?

@ symbols provide context to Cursor's AI: @Files references specific files, @Folders references directories, @Codebase searches your entire project, @Docs queries official documentation, and @Web searches the internet. They dramatically improve AI accuracy.

What are Cursor Rules?

Cursor Rules are custom instructions in a .cursorrules file that tell the AI how to generate code for your project. They enforce coding standards, preferred libraries, file organization, and team conventions automatically.

Cursor Tutorial - Master AI-Powered Development with Cursor 0.45.14

💡 What You'll Learn

Use Cmd+L (Ctrl+L) to open the AI Chat sidebar
Master @ symbols for providing context
Ask effective questions for debugging and understanding
When to use Chat vs. Cmd+K vs. Composer

💬 What is AI Chat?

AI Chat (Cmd+L) is your conversational AI assistant powered by Claude 4.5 Sonnet. Unlike Cmd+K which edits code directly, Chat is perfect for:

🤔 Understanding complex code
🐛 Debugging errors
💡 Getting implementation suggestions
📚 Learning new concepts
🔍 Exploring your codebase

🔑 Quick Start:

Press Cmd+L to open Chat
Type your question in natural language
Use @ symbols to add context (files, folders, docs)
Get instant answers with code examples

⌨️ Essential Shortcuts

Action	Mac	Windows/Linux
Open AI Chat	Cmd+L	Ctrl+L
Send message	Enter	Enter
New line in message	Shift+Enter	Shift+Enter
New chat	Cmd+Shift+L	Ctrl+Shift+L

🎯 The Power of @ Symbols

@ symbols are the secret to getting great answers. They give the AI context about your codebase.

@Files

Reference specific files

How does @src/utils/auth.ts handle authentication?

@Folders

Reference entire directories

Explain the structure of @src/components/

@Codebase

Search across your entire project

@Codebase where do we handle user login?

@Docs

Query official documentation

@Docs React how do I use useEffect?

@Web

Search the internet for current info

@Web what's new in Next.js 15?

🎯 Real-World Examples

Example 1: Debugging an Error

// Bad question (no context):

Why is my code broken?

// Good question (with context):

I'm getting "Cannot read property 'map' of undefined" in @src/components/UserList.tsx
What's causing this error?

Example 2: Understanding Code

Explain how @src/lib/api.ts handles API retries and error handling

// AI will analyze the file and explain the retry logic, error handling patterns, and best practices

Example 3: Implementation Guidance

@Codebase we need to add rate limiting to our API.
Show me how other endpoints handle rate limiting and suggest where to add it

Example 4: Learning Best Practices

@Docs Next.js what's the best way to implement server-side authentication in App Router?

✍️ Writing Effective Chat Prompts

✅ Good Prompts

"Explain how @file.ts works"
"Why is this error happening?"
"What's the best way to..."
"@Codebase where do we handle..."
"Show me examples of..."
"How can I optimize..."

❌ Bad Prompts

"Fix my code" (use Cmd+K)
"Help" (too vague)
No @ symbols for context
Asking for file creation (use Composer)
Multiple unrelated questions

🔄 When to Use What?

I want to...	Use
Understand how code works	Chat (Cmd+L) ⭐
Debug an error	Chat (Cmd+L) ⭐
Edit existing code	Cmd+K
Write new code	Tab or Composer
Get implementation suggestions	Chat (Cmd+L) ⭐
Explore the codebase	Chat + @Codebase ⭐

⚡ Pro Tips

💡 Tip 1: Always use @ symbols - they 10x the quality of answers

💡 Tip 2: Chat remembers conversation history - follow up with clarifying questions

💡 Tip 3: Use "Apply" button in chat responses to insert code directly

💡 Tip 4: Start new chats (Cmd+Shift+L) for unrelated topics to keep context clean

💡 Tip 5: Reference errors directly - copy-paste error messages for faster debugging

🎓 Practice Exercise

Try These Now:

Press Cmd+L and ask: "@Codebase what are the main features of this project?"
Pick a complex file and ask: "Explain @path/to/file.ts in simple terms"
Find an error in your code and ask Chat to debug it
Use @Docs to learn about a framework feature you're unfamiliar with
Try @Web to search for the latest best practices

📊 Chat vs. Other Tools - Quick Reference

💬

Chat (Cmd+L)

Questions, understanding, debugging

✏️

Inline (Cmd+K)

Quick edits, refactoring

⚡

Tab

Writing new code

🐛 Common Issues & Solutions

AI gives generic answers

Use @ symbols to provide file/folder context. Be specific about what you're asking.

Chat is slow

Check your internet connection. Large codebases need indexing time. Try referencing specific files instead of @Codebase.

@Codebase doesn't work

Wait for indexing to complete (check bottom status bar). Make sure your project isn't too large (>100MB).

🔗 Next Steps

Now learn how to make multi-file changes with Composer: Composer Tutorial →

Cmd+L AI Chat - Your AI Programming Partner