This document provides an overview of massive MIMO (Multiple Input Multiple Output) technology. Massive MIMO involves using a large number (tens to hundreds) of antennas at base stations to serve multiple single-antenna users simultaneously. It can dramatically increase network capacity and spectral efficiency while improving energy efficiency. Challenges include developing accurate channel models, addressing issues like pilot contamination, and designing low-cost hardware to implement massive MIMO on a large scale. Overall, massive MIMO is seen as a promising technology to meet future wireless communication needs but requires further research to realize its full potential benefits.