Parallel - (Synchronous|Asynchronous)
1 - About
Asynchronous programming is notoriously difficult because the order of operations is highly unpredictable.
2 - Articles Related
3 - Type
3.1 - Synchronous
The application thread waits while the server (such as IO device) performs a request and returns a status code when the request is complete.
3.2 - Asynchronous
Asynchronous allows an application to issue multiple requests and continue executing while the server performs the request. This type of request can improve an application’s throughput because it allows the application thread to continue with other work while an request operation is in progress.