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> **Possible Duplicate:**  
> 
> [Green Threads vs Non Green Threads](https://stackoverflow.com/questions/5713142/green-threads-vs-non-green-threads) 
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Why are Java threads implemented at the user level in the JVM called "green threads"? Is it by analogy to environmentalism, meaning to suggest that they are less wasteful than OS threads, or something else?

EDIT: Some references to where the term is used:

* [Wikipedia](http://en.wikipedia.org/wiki/Green_threads)
* [Java threads FAQ](http://www.codestyle.org/java/faq-Threads.shtml)
* [Java documentation](http://java.sun.com/docs/hotspot/threads/threads.html)