Category theory is a branch of mathematics that studies the structure of mathematical objects, such as sets, groups, and topological spaces. It provides a unified framework for understanding the relationships between these objects and their properties.

A category is a collection of objects and morphisms. The objects are the mathematical structures that are being studied, and the morphisms are the relationships between these objects.

A morphism is a relationship between two objects in a category. It is a function that preserves the structure of the objects.

Category theory is a foundation for other branches of mathematics. It provides a unified framework for understanding the relationships between different mathematical structures and their properties.

Category theory has been used in computer science to develop new programming languages, design new algorithms, and verify the correctness of software.