OpenCyc is the open source version of the Cyc technology, the world’s largest and most complete general knowledge base and commonsense reasoning engine. OpenCyc can be used as the basis for a wide variety of intelligent applications. This is release 1.0 of OpenCyc featuring the complete Cyc ontology of over 260,000 terms and their definitional assertions numbering over 1.8 million. OpenCyc requires about 500MB of disk space and performs best with over 512 MB RAM. One GB of RAM is recommended for Cyc when accessed by Java applications.