A second-bid auction is one where all bidders submit their maximum willingness to pay, and then the bidder willing to pay the most pays what the second-highest bidder was willing to pay. An English auction is where bidders submit bids which they will have to pay, with the idea that once the second-highest bidder will stop raising the bid once they pass their threshold.

There's a lot of theoretical work showing that second-bid auctions are all-around more efficient. English auctions can encourage the highest bidder to overbid, and the winner's curse refers t... (read more)