Chapter 9Geolocation

When I was a child, my parents took me to Manhattan. While walking around, we came across a big map of the city. On the map was a big circle saying “You are here.” I clearly remember asking my parents how the map knew where we were. Many years later, I relived the moment when I realized that web sites were sending ads targeted to my location. Again, I asked how they knew where I was.

The answer to my first question is pretty obvious. The person who made the map knew where it would be placed. The answer to the second is the subject of this chapter: geolocation.

Geolocation is the process of determining where in the world a device or user is. Geolocation is useful for advertisers, developers, and the average consumer. In short, ...

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