Dutch privacy regulators got Google to agree to let people using Wi-Fi routers or mobile phones the option to keep their names and locations out of a company database simple by adding _nomap to the end of a router’s name.
Google uses data from routers to locate mobile phones within broadcast range of the routers, which enables Google to offer location based advertising to its customers. This is e.g. the basis for “hyper-local” advertising. If many people opt out of the registry, Google’s ability to offer location-based services could be compromised. The company would then have to use mobile phone tower locations and the Global Positioning System to determine a phone’s location, which could result in less accuracy and greater use of battery power.
Although Google made the agreement with the Dutch Data Protection Authority, it applies to everywhere Google is active. Source: New York Times