This chapter gives an introduction to Precision Agriculture (PA) with a short historic pathway of the development and the status of current available technologies. Part of this description also provides an overview of some of the economic barriers and technical obstacles when applying variable-rate application. This chapter also notes that the adoption of several specific variable-rate application technologies have been modest in recent years. However, in contrast the adoption of auto-steering has been significant in the last decade. The last section describes the overall aim of the book and an overview of each chapter in the book. Each chapter address a different topic starting with an overview of technologies that are currently available, followed by specific Variable-Rate Technologies such as VRT fertilizer application, VRT pesticide application, site-specific irrigation management, Auto-steering and Controlled Traffic Systems. Finally, the chapter looks into new developments of autonomous systems with an example of robotic seeding, farm information management in precision agriculture and different methods on the adoption of PA. The last chapter focuses on how PA can fulfil the current policy trends on environmental regulations.