This document provides an overview of massive MIMO technology in 5G networks. It begins with an introduction to 5G and a literature review. It then discusses 5G technology, including spectrum deployment, features, architecture and challenges. It also covers MIMO in 4G LTE networks. The main topic of massive MIMO in 5G is then explained, including its construction, operation modes, limitations and the issue of pilot contamination. Applications and the scope of massive MIMO are discussed before concluding with a summary of the key points.