The book will give a deeper understanding on the environment and human behaviour. There are described the relationships between organisms in the ecosystem. The work aims to:1. Understand the different components present in the environment;2. Understand the environmental factors affect the organisms;3. Understand the structure and function of biotic and abiotic components present in an ecosystem;4. Know the importance of natural resources (biodiversity and life under sea, and their management;5. Understand the fundamentals of sustainable development ant its goals;6. Relate how human activities influence the environment (climate change-pollution, management of wastes;7. Contribute significantly in the decision-making with regard to environment issues and to prevent further degradation of the environment.