I found in Wikipedia that Sun announced in 2007, jvm and javac went open-source. I thought both were opensource from the beginning.
So is OpenJDK another synonym for JDK and HotSpot for jvm.
OpenJDK is a JDK provided by somebody else. Can't remember by whom.
The current JVM provided by Sun/Oracle is called HotSpot because it seeks hot spots of use in the code (places where code is more intensively used) for "just-in-time" optimisation.
OpenJDK is an open-source implementation of the Java Platform, Standard Edition (Java SE) specifications.
......
......
......
Sun's Commercial Distribution of the JDK
People who want the benefits of commercial support and predictability can choose to use Sun's commercial distribution of the Java SE JDK or JRE.
Sun'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, Sun will continue to use that code in commercial releases until it is replaced by fully-functional open-source alternatives.