This lecture explores the process of composting, focusing on the benefits and techniques involved. The instructor visits two friends, Marguerite and Maël, showcasing different composting methods. The lecture covers the importance of composting, the ideal carbon to nitrogen ratio, materials suitable for composting, and the process of cool or passive composting. Additionally, vermicomposting using earthworms is explained, highlighting the dos and don'ts, practical process, and the collection of compost tea for plant growth.