The document discusses key concepts around sustainable development and the environment. It begins with defining what it means to be environmentally friendly or eco-friendly, noting the importance of conserving natural resources. Next, it outlines 15 easy ways for individuals to become more environmentally friendly, such as being more aware of resource usage, practicing conservation, and reducing harmful chemicals. It then covers energy and waste management, defining waste-to-energy as a process for recovering energy from non-recyclable waste. Finally, it discusses principles of sustainable tourism, including enhancing community well-being while protecting the natural environment.