生物学（希腊语：βιολογία；拉丁语：biologia；德语、法语：biologie；英语：biology）或称生物科学（biological sciences）、生命科学（英语：life sciences），是自然科学的一大门类，由经验主义出发，广泛研究生命的所有方面，包括生命起源、演化、分布、构造、发育、功能、行为、与环境的交互关系，以及生物分类学等。现代生物学是一个庞大而兼收并蓄的领域，由许多分支和分支学科组成。然而，尽管生物学的范围很广，在它里面有某些一般和统一概念支配一切的学习和研究，把它集成成单一的，和连贯的领域。在总体上，生物以细胞作为生命的基本单位，基因作为遗传的基本单元，和进化是推动新物种的合成和创建的引擎。今天人们还了解，所有生物体的生存以消耗和转换能量，调节体内环境以维持稳定的和重要的生命条件。

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, identification and taxonomy. Modern biology is a vast and eclectic field, composed of many branches and subdisciplines. However, despite the broad scope of biology, there are certain general and unifying concepts within it that govern all study and research, consolidating it into single, coherent field. In general, biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the synthesis and creation of new species. It is also understood today that all the organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable and vital condition.