What actually happens after I put my address into one of those instant home-value sites?

Automated valuation models pull from public records and recent nearby sales without anyone walking through your home, so an algorithm never sees a renovated kitchen, a finished basement, deferred maintenance, or a problem like foundation cracks. That gap is why an online estimate can diverge sharply from what a local agent's in-person comparative market analysis produces, since the agent actually inspects the property and picks truly comparable recent sales. Treat the online number as a starting point, not a price.