The goal of the planned high-energy high-luminosity polarized electron-ion collider (EIC) is a
detailed understanding of the QCD dynamics that underlies the nucleons and nuclei. With advances in
experimental technique and theoretical understanding over the past several decades, jets have become
precision tools in the exploration of QCD in collider environments. Therefore, precision jet measurements
have the potential to be important components of the electron-hadron and electron-nucleus EIC physics
programs. One property of jets that may prove especially useful is that their substructure, i.e. their
internal energy distribution, can be rigorously defined and studied systematically. This contribution
will discuss possible substructure observables at an EIC as well as outline their applications and
experimental aspects of their measurement.