It's free 2 business day shipping. Some items/places can be shipped with a carrier that delivers on weekends, but many can't with the carrier's 2-day option. You (Amazon) might have to pay for the carrier's next-day shipping to get weekend delivery, so it can be impossible to get something delivered on a Saturday when ordering on a Thursday.<p>The annoying thing with Amazon shipping is that sometimes you can't order an expedited shipping option if needed, even for prime items. This tends to be due to third-party sellers that participate in the prime program, but for some reason don't offer any other option but the free 2-day. There have been times when I've paid the extra for next-day air for some things, though it tends to be very expensive.