Is the mobile communication between script and device is Synchronous/Asynchronous?

I have one basic question.

When we execute the script, how it exactly executed in device.

Each statement in the script sent to Appium and then the statement is executed in Mobile and the response sent back to test script through Appium? or a fragment or entire script sent to Appium?

I am hoping execution happens statement by statement. Can someone correct me i am wrong?