A morphism is a map between two objects in an abstract category.
1. A general morphism is called a homomorphism,
2. A morphism in a category is a monomorphism if, for any two morphisms , implies that ,
3. A morphism in a category is an epimorphism if, for any two morphisms , implies ,
4. A bijective morphism is called an isomorphism (if there is an isomorphism between two objects, then we say they are isomorphic),
5. A surjective morphism from an object to itself is called an endomorphism, and
6. An isomorphism between an object and itself is called an automorphism.