生态学（德语：Ökologie），是德国生物学家恩斯特·海克尔于1866年定义的一个概念：生态学是研究生物体与其周围环境（包括非生物环境和生物环境）相互关系的科学。德语Ökologie（最初：Oecologie）是由希腊语词汇Οικοθ（家）和Λογοθ（学科）组成的，意思是“研究居住在同一自然环境中的动物（Lebewesen）的学科”，目前已经发展为“研究生物与其环境之间的相互关系的科学”。环境包括生物环境和非生物环境，生物环境是指生物物种之间和物种内部各个体之间的关系，非生物环境包括自然环境：土壤、岩石、水、空气、温度、湿度等。

Ecology (from Greek:οἶκος, "house", or "environment"; -λογία, "study of") is the scientific analysis and study of interactions among organisms and their environment. It is an interdisciplinary field that includes biology, geography, and Earth science. Ecology includes the study of interactions organisms have with each other, other organisms, and with abiotic components of their environment. Topics of interest to ecologists include the diversity, distribution, amount (biomass), and number (population) of particular organisms, as well as cooperation and competition between organisms, both within and among ecosystems. Ecosystems are composed of dynamically interacting parts including organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, pedogenesis, nutrient cycling, and various niche construction activities, regulate the flux of energy and matter through an environment. These processes are sustained by organisms with specific life history traits, and the variety of organisms is called biodiversity. Biodiversity, which refers to the varieties of species, genes, and ecosystems, enhances certain ecosystem services.