Although liquid crystal displays (LCDs) have been available for over half a century, they were always taken as niche market products because of their rather poor performance: small viewing angles, long response time, and lack of large-area panels. The situation has changed dramatically since the availability of the active matrix (AM) LCDs, specially the amorphous silicon (a-Si:H) thin film transistor (TFT) driven LCDs. The displays manufactured on TFT LCDs will be major driving force for advancement of the TFT technology in the near future. New key impact areas of TFTs will be flexible electronics, integrated circuits, sensors, detectors, light emitting diodes, etc. Industry R&D activities have been aiming at improving the cost, yield, and throughput of large-area panels. Academic research in many universities has helped in the understanding of material properties responsible for the TFT performance as well as the underlying chemistry and physics of the fabrication processes.