What Is the Definition of the System Read Call?

Hussein: Calling read from the application will do exactly that. Read here is an actual operating system call and it's called synchronous I.O. He says when you actually make a call and that call is just blocked sitting there and don't doing anything, the CPU will not leave our instructionless process in the CPU. Hussein: You can't block the app just because we're not doing anything. The app also has other things to do technically. And this is where the asynchronous I.O was born.