Resource Description Framework (RDF)
The RDF module provides Drupal's core support for the W3C's Resource Description Framework (RDF) standard. This standard allows for modeling and sharing knowledge in a decentralized way, breaking down information into subject-predicate-object triples for data exchange between systems.
If you are new to RDF, watch this introduction.
RDF is a W3C standard for modeling and sharing distributed knowledge based on a decentralized open-world assumption. Any knowledge about anything can be decomposed into triples (3-tuples) consisting of subject, predicate, and object; essentially, RDF is the lowest common denominator for exchanging data between systems.
Branches
4.0.x = current main branch
3.0.x = only major bug fixes and security
2.0.x = only security. Hoping to unsupport when D10 is EOL