Versioning ensures backward compatibility when updating RESTful APIs. Common strategies include URI versioning (/v1/resource), query parameters (/resource?version=1), and header-based versioning (Accept: application/vnd.myapi.v1+json). URI versioning is the most widely used due to its simplicity. Query and header-based methods offer more flexibility but require better client-side handling. Versioning prevents breaking changes, allowing developers to introduce new features while maintaining older versions. A well-planned versioning strategy ensures smooth API evolution without disrupting existing consumers.