“What is Gevent, anyway? According to the gevent webpage:
    gevent is a coroutine-based Python networking library that uses greenlet to provide a high-level synchronous API on top of the libevent event loop.

That’s a succinct definition, and it identifies all the technologies and implementation architecture of gevent, but it doesn’t really give a good “beginner’s view.” The quickest way I can think of to define it is to say: Gevent gives you threads, but without using threads…”

http://blog.pythonisito.com/2012/07/introduction-to-gevent.html