Jets at electron-positron colliders

We provide a pedagogical introduction to the physics of hadronic jets and event shapes at electron-positron colliders. We present some of the main jet definitions and event shape observables studied at lepton colliders and discuss how to produce theoretical predictions in perturbative quantum chromodynamics (QCD), both at fixed order and with resummation or parton showers. We further introduce important topics in jet substructure that have seen developments in a lepton collider environment, such as the Lund jet plane, Soft Drop, and quark-gluon jet discrimination. Finally, we briefly elaborate on selected topics, such as flavoured jets, hadronic decays of the Higgs boson, and non-perturbative effects.