The article addresses frequently asked questions about the ISAPP postbiotic definition. The ISAPP defines postbiotics as preparations of inanimate microorganisms and/or their components that confer a health benefit on the host. The definition was developed through a consensus process involving experts from various fields. The definition focuses on inanimate microbes and their components, not microbial metabolites, as metabolites are not living and cannot have an 'after-life'. While metabolites can be part of a postbiotic preparation, they are not mandatory. The term 'postbiotic' was chosen to distinguish it from other terms like 'probiotic' and 'paraprobiotic', which refer to live microbes. The term 'inanimate' is used to describe non-viable microbes, and it is not the same as 'non-viable'. The definition includes substances produced in situ, but the postbiotic itself is defined as the administered material, not the resulting metabolic byproducts. The definition allows for a wide range of microorganisms as progenitors, and postbiotics can contain a mixture of microorganisms. The mechanism of action of complex postbiotics is not always known, and it is not necessary to determine the relative contribution of each component. The definition requires that the progenitor microbe be clearly identified and the production process described. Safety and efficacy must be demonstrated for postbiotic products. The article also discusses the commercial availability of postbiotic products and the importance of proper characterization and quantification. The ISAPP definition aims to provide a clear and consistent framework for the use of postbiotics, supporting innovation and communication in the field.The article addresses frequently asked questions about the ISAPP postbiotic definition. The ISAPP defines postbiotics as preparations of inanimate microorganisms and/or their components that confer a health benefit on the host. The definition was developed through a consensus process involving experts from various fields. The definition focuses on inanimate microbes and their components, not microbial metabolites, as metabolites are not living and cannot have an 'after-life'. While metabolites can be part of a postbiotic preparation, they are not mandatory. The term 'postbiotic' was chosen to distinguish it from other terms like 'probiotic' and 'paraprobiotic', which refer to live microbes. The term 'inanimate' is used to describe non-viable microbes, and it is not the same as 'non-viable'. The definition includes substances produced in situ, but the postbiotic itself is defined as the administered material, not the resulting metabolic byproducts. The definition allows for a wide range of microorganisms as progenitors, and postbiotics can contain a mixture of microorganisms. The mechanism of action of complex postbiotics is not always known, and it is not necessary to determine the relative contribution of each component. The definition requires that the progenitor microbe be clearly identified and the production process described. Safety and efficacy must be demonstrated for postbiotic products. The article also discusses the commercial availability of postbiotic products and the importance of proper characterization and quantification. The ISAPP definition aims to provide a clear and consistent framework for the use of postbiotics, supporting innovation and communication in the field.