Twisted has been around a long time in the Python world. Pioneering the Deferred abstraction, which later turned into Promises and found their way into JavaScript, it is a fertile ground for asynchronous I/O experimentation. Through its groundbreaking protocol/transport design that some of us might take for granted these days, and a strict adherence to unit testing and representing things through abstract interfaces, it lets you talk a lot of different network protocols without really having to know everything about them.

It can make your application awesome.