“The framework is also single-threaded, and its model relies on concurrency which is based on an event loop. It operates in a non-blocking mode, which means that the programs are not blocked but allowed  to continue with execution. What happens is that it registers the callback, and then allows the program to continue with the process of execution. Due to the ability of the framework to handle concurrent operations effectively without having multiple threads in the state of execution, the applications are always in a position to scale well.”