The OpenCyc Platform is your gateway to the full power of Cyc, the world's largest and most complete general knowledge base and commonsense reasoning engine. OpenCyc contains hundreds of thousands of Cyc terms organized in a carefully designed ontology. Cycorp offers this ontology at no cost and encourages you to make use of, and extend, this ontology rather than starting your own from scratch. OpenCyc can be used as the basis of a wide variety of intelligent applications such as:

•  rich domain modeling
•  semantic data integration
•  text understanding
•  domain-specific expert systems
•  game AIs

to name just a few.

Release 4.0 of OpenCyc includes:

•  The core Cyc ontology whose domain is all of human consensus reality. The current release includes:
  •  ~239,000 terms (up from ~177,000 terms in the previous release)
  •  ~2,093,000 triples (up from ~1,500,000 in the previous release)
  •  Select class (direct and indirect) instance counts:
    •  'place': ~19,000
    •  'organization': ~26,000
    •  'predicate': ~22,000
    •  'business related thing': ~28,000
    •  'person': ~12,700
  •  ~69,000 owl:sameAs links to external (non-Cyc) semantic data namespaces:
    •  DBpedia: ~47,000 links, including 696 links to the DBpedia ontology
    •  UMBEL: ~21,000 links
    •  WordNet: ~11,000 links
    •  Wikicompany: 1028 links
    •  CIA World Factbook: 172 links
    •  RDFAbout SEC company identifiers: 661 links
    •  RDFAbout states and counties: 71 links
    •  FOAF: 44 links
  •  English strings (a canonical one and alternatives) corresponding to each concept term, to assist with search and display.
•  A java-based Cyc Inference Engine and the Cyc Knowledge Base Browser
•  Documentation and self-paced learning materials to help users achieve a basic- to intermediate-level understanding of the issues of knowledge representation and application development using Cyc.
•  A specification of CycL, the language in which Cyc (and hence OpenCyc) is written.
•  A specification of the Cyc API for application development.