This document discusses various topics related to geo applications and location-based services. It begins with introductions to maps, their uses and inaccuracies. It then covers critical points of geo apps like localizing content and managing digital rights. Various location data sources and why location-based services are used are explained. Opportunities with APIs from Google Maps, Yandex Maps, OSM and Bing Maps are presented. Finally, it discusses technologies like latitude/longitude and projections, and how data, people and revenue factor into geo applications.