面相学是中国五术中的一种学问，主要从人的面上或身上的特征、行为举止等来判断一个人的性格和健康，从而推测一个人的命运。现今面相学融合西洋解剖学，最基本分为三质，心性质、筋骨质、营养质，从肤色五官高矮胖瘦皆可从这三质来论，三质定位后再依据流年细论，并搭配五官。（若三质熟悉则可加入中国相法中的“五行”来分类）相绝对不单论，定要配合整体，否则将断章取义判断失策。

面相的记载很早。《礼记》载：“凡视上于面则傲，下于带则忧，倾则奸。”又如勾践平吴之后，范蠡深知勾践为人“长颈鸟喙，可与共患难，不可与共乐”，遂与西施一起泛舟齐国，变姓名为鸱夷子皮。其他如苏秦是“骨鼻剑脊”；项羽乃“目有重瞳”；周亚夫是“纵理入口”，纵理即法令，相术谓纵理入唇为饿死之相；刘秀则是“隆准日角”。

Physiognomy (from the Gk. physis meaning "nature" and gnomon meaning "judge" or "interpreter") is the assessment of a person's character or personality from his or her outer appearance, especially the face. The term can also refer to the general appearance of a person, object, or terrain, without reference to its implied characteristics, as in the physiognomy of a plant community.