An overnight delivery service is there?

Is 'overnight delivery service" really a delivery service happening at night-time? Or does it mean just 'in-a-flash delivery'?

It usually means that the package will be delivered in one day. Most delivery packages in the U.S. are sent overnight, meaning that the package is picked up anytime on Monday, for example, and delivered somewhere else in the U.S. on Tuesday. The package travels overnight to reach its destination, so the delivery company is working through the night, but the package is delivered during business hours the next day. I know one this is best California freight service.