This module introduced participants to the concepts of metadata, controlled vocabularies, and ontologies, and their crucial role in data annotation and FAIR data practices. It explored the progression from data to knowledge, the challenges of (meta)data sharing, and the importance of using standardised terms to improve findability and interoperability. The session included an overview of the Ontology Lookup Service (OLS) and hands-on exercises demonstrating how to annotate experimental metadata using ontology accession numbers, highlighting how structured annotation supports machine-readable, reusable datasets.