What is the use of Apex Continuation object in Salesforce?

on Continuation object in Apex – Asynchronous callouts for long running request – Live Demo
We may run into scenario in Salesforce project, where we need call external web service but no need to wait for response. Response from external web service can be processed asynchronously and once processed it can be presented in Visualforce page.

so we can accomplish this by using  Continuation object as well.