This course in General Ecology is intended for students in the Preparatory Classes for the 2nd year of the Natural and Life Sciences at the High School of Agronomy- Mostaganem. This educational document in no way replaces the books on the subject available in the library. It is simply a summary of a few choice titles, old and recent, covering the syllabus of the teaching unit in question. The course is presented in five chapters with sufficient illustrations to facilitate understanding. The first chapter focuses on a few general points about ecology, namely the concept of the ecological system and the various areas of intervention. The second chapter presents the environment and its interactions with the various elements that surround it. The third chapter deals with abiotic factors, i.e. the complexity of climatic and edaphic elements. The fourth is devoted to biotic ecological factors, covering all the interactions between different living beings. Finally, the fifth deals with the structure and functioning of the various types of ecosystems that characterize our biosphere.