Missing transverse momentum (MET) is a key concept in particle physics, particularly in experiments involving the study of high-energy collisions. MET refers to the imbalance in the transverse momentum of particles observed in the detector after a collision event. This can be caused by undetected particles such as neutrinos or hypothetical particles like dark matter, which do not interact strongly with matter and thus escape detection. The measurement of MET is critical for identifying the presence of such invisible particles and for studying the overall momentum balance in an event. Researchers use sophisticated algorithms and techniques to reconstruct MET and extract valuable information about the underlying physics processes that occur in high-energy collisions.