As digital systems cover all personal and professional activities, artificial intelligence is now everywhere. In this context, it is crucial for systems and decisions to be understandable for humans, in a human-in-the-loop process. This global objective is known as eXplainable Artificial Intelligence (XAI). In this chapter, we argue that fuzzy logic is a key concept for XAI as it offers a theoretical framework that is closer than many others to human cognition, human reasoning and human intuitions. We exemplify the many advantages fuzzy logic offers to the XAI domain.