The document discusses the growth of location-based service users from 18.9 million in 2007 to an estimated 486 million in 2012, and how 80% of purchases are made within 10 miles of home. It provides an overview of techniques for building a location-based application using IP geolocation, HTML5 permissions, and mixing the approaches. The document concludes with best practices for building location-based applications, such as giving users privacy and feedback options.