Interdisciplinarity is a way for different research fields to come together and create new knowledge. It can lead to the formation of entirely new disciplines or disappear over time. By studying how journals cite each other, researchers can see how fields evolve from being multidisciplinary to interdisciplinary. The main difference between interdisciplinary and disciplinary fields is that interdisciplinary fields are newer. By focusing on how research fields change over time, we can understand how knowledge grows and changes in the scientific community.