How does "Make a Best Offer" work?

On many "Buy It Now" sales we have on eBay, you also have the option to "Make a Best Offer."

"Make a Best Offer" means that you can make one offer on an item that will either be accepted or declined and the listed shipping will be added in checkout.  Please note shipping charges are non-negotiable and can not be included in a best-offer.  Asking for other items not included in the item listing is also invalid and will not be recognized by the automated filter.

Note: A Best Offer is just like a bid and is a commitment to purchase an item if accepted by the seller.

You can find more information on Best Offers at the following ebay link: http://pages.ebay.com/help/sell/best-offer.html