Amorphous oxide semiconductor transistors have been a mature technology in display panels for upwards of a decade, and have recently been considered as promising back‐end‐of‐line (BEOL) compatible channel materials for monolithic 3D applications. However, achieving high‐mobility amorphous semiconductor materials with comparable performance to traditional crystalline semiconductors has been a long‐standing problem. Recently it has been found that greatly reducing the thickness of indium oxide, enabled by an atomic layer deposition (ALD) process, can tune its material properties to achieve high mobility, high drive current, high on/off ratio, and enhancement‐mode operation at the same time, beyond the capabilities of conventional oxide semiconductor materials. In this work, we review the history leading to the re‐emergence of indium oxide, its fundamental material properties, growth techniques with a focus on ALD, state‐of‐the‐art indium oxide device research, and the bias stability of the devices.This article is protected by copyright. All rights reserved