Measurement of jet substructure and jet fragmentation using the ATLAS detector

Measurements of the internal properties of jets allow QCD to be studied in a new energy regime. In this talk, we discuss recent measurements of jet substructure and jet fragmentation, which were performed using data collected by the ATLAS experiment at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. For jet substructure, a comprehensive suite of substructure observables are measured for jets reconstructed with the soft-drop algorithm applied. In addition, a measurement of the Lund Plane is performed using charged particles. The fragmentation properties of jets, such as the jet charge and summed fragmentation function, are also measured using charged particles.