This definition provides a basic perspective of the state of knowledge for a given ecosystem, describes the important ecosystem components and functional processes, and provides a mechanism for ecosystem understand­ing through the integration of components and functional processes. Ecosys­tem characterization provides an understanding of ecosystem to assist in integration of complex ecological information, identification of gaps and lacunae in information, establishment of research priorities, assessment of environmental impacts, and for comprehensive planning. Ecosystem charac­terization can be regarded as one of a number of tools required to protect and manage living resources. The approach to the characterization process involves the delineation of the physical boundaries of the system, prepara­tion of a conceptual ecosystem model, synthesis and analysis of existing knowledge using the model as a blueprint, and preparation of the character­ization report. Ecosystem characterization provides an important ecological foundation from which to plan and manage for the future of our natural resources.