Checkpoint Restart

Does rsync have any type of checkpoint restart? If a transmission fails, does it have to be restarted manually, or will it continue trying from the point of failure?

Interrupted transfer of a file

If a new file is being sent and communication is lost..Is the partial file retained and then only the 'changed' information is sent on the next transfer? Or is the partial file lost? Is there anything like a completion code that can be captured to use for a check/restart? We often have bad or