Amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) invented only one decade ago are now being commercialized for active-matrix liquid crystal display (AMLCD) backplane applications. They also appear to be well positioned for other flat-panel display applications such as organic light-emitting diode (AMOLED) applications, electrophoretic displays, and transparent displays. The objectives of this contribution are to overview AOS materials design; assess indium gallium zinc oxide (IGZO) TFTs for AMLCD and AMOLED applications; identify several technical topics meriting future scrutiny before they can be confidently relied upon as providing a solid scientific foundation for underpinning AOS TFT technology; and briefly speculate on the future of AOS TFTs for display and non-display applications.