How offer deadlines actually work

When submitting an offer on a home, a reply deadline is usually included.  Whether that's upheld is another story, but there is one included on the offer.  Well... what's it like when the reverse situation happens and the seller indicates when all offers have to be submitted by?  It's a very real scenario in a hot market or when a property is rare enough that a seller thinks there will be a frenzy for it.  Let's take a look at it, what it means, and the potential outcomes (other than frustration).