Terminology services are software functions that provide access to terminology resources and their features. They can simplify the retrieval, testing, and querying of SNOMED CT® by hiding the complexity of these functions behind a standardised application programming interface (API). The most popular terminology services standard today is the HL7® FHIR® terminology services API. This chapter first explains what terminology services are and then focuses on how to use the HL7® FHIR® terminology services API to access SNOMED CT®. It also explores syndication services, available terminology server products, and training opportunities.