Abstract: Since the discovery of the Higgs boson in 2012, many related measurements have moved into the Lorentz-boosted regime. One feature of this regime is collimated sprays of particles called jets. Understanding jets and jet substructure has therefore become of vital interest to particle physicists.

In this seminar, I present recent measurements of jet substructure quantities, which can help us better understand multijet systems and pave the way to understanding substructure at future colliders. In addition, these measurements help us to improve machine learning taggers by reducing systematic uncertainties. I also detail my work on jet reconstruction and the detector hardware that makes these physics analyses possible.