OpenJDK is an open-source implementation of the Java Platform, Standard Edition (Java SE) specifications. In May 2007, Sun released a fully buildable Java Development Kit (JDK) version for Java SE to the OpenJDK Community as free software under the GNU General Public License version two (GPLv2). Sun announced the Interim Governing Board for the OpenJDK community. Sun also announced that OpenJDK-based implementations can use the Java SE 6 Technical Compatibility Kit (JCK) to establish compatibility with the Java SE 6 specification. For more information, the following links go to the OpenJDK community, project, source, and forum sites.
Oracle's Commercial Distribution of the JDK
People who want the benefits of commercial support and predictability can choose to use Oracle's commercial distribution of the Java SE JDK or JRE. Oracle's commercial JDK releases will be built from the open-source code, for the most part. Since there's some encumbered code in the JDK, Oracle will continue to use that code in commercial releases until it is replaced by fully-functional open-source alternatives. To learn more about development and deployment support options, visit the Java Support site.