Dive into the world of high-energy physics with this comprehensive lecture on High-Luminosity Large Hadron Collider (HL-LHC) theory. Explore the potential for discovering Beyond Standard Model (BSM) physics, understand the importance of probing intensity, and delve into Lagrangian models. Examine the differences between UV and IR approaches, investigate the H Sector, and learn about large and small background effects. Gain insights into supersymmetry, unexpected phenomena, and the significance of various models. Analyze the role of muons in particle physics and grasp the fundamentals of Effective Field Theory. This in-depth talk by Matthew McCullough from CERN offers a thorough exploration of cutting-edge concepts in particle physics research.