This lecture covers the principles and techniques of mass spectrometry, focusing on detectors, MS/MS, and various mass spectrometry methods such as FT-ICR-MS and Triple Quadrupole Mass Spectrometry. It explains how ions are detected, resolved, and analyzed in mass spectrometry instruments, highlighting the advantages and disadvantages of each technique. The lecture also delves into the process of protein sequencing by mass spectrometry, showcasing the importance of accurate mass measurements and stable isotopes in identifying and characterizing molecules.