| If you want to find... | Select these columns... | The Logic | | :--- | :--- | :--- | | | First Name + Last Name + Email | High precision. If email matches, it's a dupe. | | The same household | Address + Zip Code | Ignores different names (spouse/kid). | | The same company | Domain Name only | Removes 50 people from @acme.com leaving 1. | | The messy lead | Phone Number (normalized) | Removes (212) 555-1212 and 212-555-1212 . |

I’ve designed this to be less like a boring manual and more like a "detective toolkit" for cleaning up your data. Tagline: Stop hoarding copies. Start finding gold. The Setup: Why You Have 47 Copies of the Same File Let’s be honest. Your database, CRM, or CSV export is lying to you. It tells you that you have 5,000 customers. But in reality? You have 2,000 unique humans and 3,000 ghosts (typos, duplicate imports, and "John Smith" who spelled his email differently three times).