This lecture introduces the life cycle analysis, focusing on the life cycle of a toaster as an example. It covers the linear and circular visions of the toaster's life cycle, the stages of a product's life cycle, and the perspective of life cycle assessment. The instructor emphasizes the importance of considering the entire life cycle of a product, from resource extraction to waste disposal, to identify and prevent environmental impacts. The lecture also clarifies the difference between the life cycle in marketing and life cycle assessment.