# Nine Rules of Debugging 1. Understand the system 2. Make it fail, before fixing anything 3. Quit thinking and add more instrumentation 4. Use divide and conquer to locate bugs 5. Change one thing at a time 6. Keep an audit trail (experimentation record) 7. Check the “plug” first 8. Get a fresh view (pairing) 9. If you didn’t fix it, it ain’t fixed