This educational video provides a comprehensive introduction to the fundamental biological question: "What defines a living thing?" Hosted by Caroline, the lesson moves beyond simple intuition to establish a rigorous scientific framework for distinguishing living organisms from non-living matter. The video breaks down the seven essential criteria used by biologists—organization, response to stimuli, reproduction, adaptation, growth, homeostasis, and energy processing—explaining that an entity must meet *all* seven requirements to be scientifically classified as alive. The content systematically explores each criterion with clear definitions and relatable examples ranging from single-celled bacteria to complex multicellular humans. It utilizes diverse visuals, including microscopic views of cells, time-lapse footage of plant growth, and diagrams of DNA, to make abstract concepts concrete. A significant portion of the video is dedicated to a guided case study on coral, challenging viewers to apply what they've learned to determine if a stationary, rock-like structure is actually a living organism. For educators, this video serves as an excellent foundational resource for a Biology or Life Science unit. It actively models critical thinking by debunking common misconceptions (like the idea that movement is a requirement for life) and includes built-in pause points for student reflection. The concluding open-ended question about viruses provides a perfect springboard for advanced classroom debate and research, making this video versatile for introducing core biological concepts and the scientific method.