This is an introductory course on general ecology for students to understand various principles of ecology. The concept of ecology will be defined in terms of basic components, structures and processes that occur in ecosystems, fundamental populations ecology, communities and ecosystems, together with the analysis and interpretation of the distribution patterns of organisms. Biotic and abiotic factors which characterize terrestrial, freshwater and marine ecosystems will also be discussed. The productivity of these ecosystems will be compared. At the end of this course, knowledge of ecology will be applied to evaluate human impacts towards ecosystems, which have caused environmental disasters such as the greenhouse effect, depletion of the ozone layer and eutrophication. The definition, reasons and aims of conservation will also be defined.