Pervasive computing aims to create services that respond directly to their user and environment, with greatly reduced explicit human guidance. The possibility of integrating IT services directly into users’ lives and activities is very attractive, opening-up new application areas. But how has the field developed? What have been the most influential ideas and projects? What research questions remain open? What are the barriers to real-world deployment? In this chapter we briefly survey the development of pervasive computing and outline the significant challenges still being addressed.