The 1st workshop of the series, ‘Why Mappings Matter and how to make them FAIR?" was organised on April 13th by FAIR-IMPACT and the SSSOM developer community. to introduce participants to the motivation behind doing mappings and how they could benefit even more by making mappings FAIR. A series of Show and Tell presentations took place, where use cases and practices from a range of communities –spanning domains, research infrastructures, projects, task forces, and working groups– were presented. During this workshop, the Simple Standard for Sharing Ontological Mappings (SSSOM) was introdeuced as a candidate format for defining and sharing entity mappings, considering also its pivotal role in the FAIRCORE4EOSC technical specifications. The presentations was followed by a collaborative work on mapping aspects, including methodologies, formats, tools, requirements for FAIR mappings and examples. The main objective of this workshop was to define, together with different communities, the initial requirements for developing a useful framework around FAIR mappings including the requirements to adhere to the FAIR principles. The event page is available at https://fair-impact.eu/events/fairimpact-events/why-mappings-matter-and-how-make-them-fair