Some concepts feel so familiar that a definition hardly seems necessary. Sustainability and artificial intelligence, for example, are ubiquitous terms that most of us hear and even use daily. It might be tempting, then, to delve straight into the specifics of how technology relates to, for example, inequality, environmental degradation, and political stability and democracy. However, the key concepts discussed in this book are deeply ambiguous and potentially problematic. A crucial first step is consequently to explain how we use – and don’t use – concepts such as technology, solutionism, and sustainable development – the concepts also referred to in the title of this book. This chapter begins with a brief explanation of how we use the terms technology and technological change, which are central in the analyses in the following chapters. Next, key concepts related to sustainability are detailed. Sustainability, sustainable development, and the UN’s Sustainable Development Goals take the main stage, along with the various explicit and implicit assumptions associated with these.