This document discusses using ontologies to make biological and biomedical data more interoperable and FAIR (Findable, Accessible, Interoperable, Reusable). It describes several ontology services and tools provided by EMBL-EBI to help with tasks like annotating data, mapping data to ontologies, searching and accessing ontologies, and publishing structured data. It also uses the example of the BioSamples database to illustrate challenges in working with large, heterogeneous datasets and how ontologies can help address issues like normalizing descriptions and attributes to enable better searching and data integration.