Structure refers to the arrangement and organization of parts within a whole. It can be seen in various contexts, such as in buildings, where the framework supports the overall design, or in writing, where the sequence of ideas creates a coherent message. In nature, structure is evident in the way cells are organized in living organisms, or how ecosystems are arranged with different species interacting. Understanding structure helps us analyze and appreciate the complexity of systems, whether they are physical, biological, or conceptual, like language or architecture.