Category theory is used to formalize mathematics and its concepts as a collection of objects and arrows (also called morphisms). Category theory can be used to formalize concepts of other high-level abstractions such as set theory, field theory, and group theory. Several terms used in category theory, including the term morphism, differ from their uses within mathematics itself. In category theory, a morphism obeys a set of conditions specific to category theory itself. Thus, care must be taken to understand the context in which statements are made.