This document discusses the environment and what constitutes life. It begins by asking questions about what environment and life are, and noting that environment depends on what type of organism you are referring to. It then discusses humans as living organisms. The key characteristics of life are explained as highly complex organization, self-homeostasis, self-perpetuation, growth and development, interactions, adaptation, and response. There is a hierarchy of biological organization from cells to organisms to populations and communities. Humans are unique in that they modify their environment to suit themselves, whereas other organisms adapt to their environment.