This seminar starts by providing a short introduction to the field of Environmental Life Cycle Assessment (LCA) through a practical example of packaging. It will then develop the case of the Life Cycle Benefits and Impacts of the Internet; raising the different scientific challenges that LCA faces to provide relevant results for innovative technologies.--The rapid development of the Internet and the related potential impacts on and benefits for the environment deserves attention. The infrastructure that supports a university's use of the Internet has been comprehensively assessed together with overall impacts of the US Internet, using two methods of Life Cycle Assessment. A process-level study focusing on the direct as well as indirect ("embodied") energy and key pollutants (CO2, NOx and SO2) attributable to the total physical infrastructure has been performed. An Input-Output study has also been used to evaluate the impacts of both the material and the services associated with the Internet infrastructure. Results show the dominance of the impact of PCs over other equipment. The use of the Input-Output to evaluate the environmental impacts of the services linked to the university infrastructure shows that these generally missed impacts could be significant. Benefits of different Internet applications will be discussed together with different challenges (impact of End-of Life of electronic equipment, fate and exposure of flame retardants, etc.).