喺範疇論入面，範疇入面記錄咗入面嘅數學物件同埋佢哋之間嘅關係。事實上，現代數學入面每一個研究分子都有對應嘅範疇，例如線性代數對應嘅就係向量空間範疇。對於範疇呢個概念自己嘅研究叫做範疇論。
In category theory, categories record the mathematical objects and the relationships between them. In fact, every molecule studied in modern mathematics has a corresponding category, for example, linear algebra corresponds to a vector space category. The study of the concept of category is called category theory.