Tornado is a framework to build asynchronous network applications. It is developed for Python 2 and Python 3. In the preceding example, http_client is an object of the AsyncHTTPClient class of Tornado. As it is developed in a non-blocking manner, the execution does not wait until the application to finish fetching the website. It returns even before the method returns the output.

On the other hand, if it was developed as a synchronous blocking manner using the HTTPClient class of Tornado, the application will wait for the method to complete before proceeding further.