Why async/await?

When we call a simple non-async function we have also to wait for execution time .
For example:

simple ( ) ;
fn simple ( ) { 1 + 1 }

So, what is the difference between waiting for calculation 1 + 1 and waiting for web response ?

You might want to read up on the subject in the Async Rust Book.
It covers motivation, how to get started, and how to use it.


The short answer is that if the thing you are waiting for is IO, then you don't actually have to wait and can do something else in the mean-time. You may find this article illuminating.