Amorphous oxide semiconductors: From fundamental properties to practical applications

•This is the first review on indium-free AOS, which are important materials because indium is a rare and precious element.•The fundamental properties and physics of In-free AOSs are reviewed.•The progress and achievements of In-free AOS TFTs are reviewed in detail.•The application of indium-free AOS in different fields, such as displays, transparent electrodes is also introduced.