Per- and polyfluoroalkyl substances (PFAS) are aclass of substances for which there are widespread concerns abouttheir extreme persistence in combination with toxic effects. It hasbeen argued that PFAS should only be employed in those uses thatare necessary for health or safety or are critical for the functioningof society and where no alternatives are available ("essential-useconcept"). Implementing the essential-use concept requires asufficient understanding of the current uses of PFAS and of theavailability, suitability, and hazardous properties of alternatives. Toillustrate the information requirements under the essential-useconcept, we investigate seven different PFAS uses, three inconsumer products and four industrial applications. We investigatehow much information is available on the types and functions of PFAS in these uses, how much information is available onalternatives, their performance and hazardous properties and,finally, whether this information is sufficient as a basis for deciding onthe essentiality of a PFAS use. The results show (i) the uses of PFAS are highly diverse and information on alternatives is oftenlimited or lacking; (ii) PFAS in consumer products often are relatively easy to replace; (iii) PFAS uses in industrial processes can behighly complex and a thorough evaluation of the technical function of each PFAS and of the suitability of alternatives is needed; (iv)more coordination among PFAS manufacturers, manufacturers of alternatives to PFAS, users of these materials, governmentauthorities, and other stakeholders is needed to make the process of phasing out PFAS more transparent and coherent.