A
- Absolute auction
- An auction in which the item sells to the highest bidder, whatever the price.
- Advertised value
- A value a seller displays for an item, often as a reference point that makes a lower price look like a saving. It may be based on MSRP, a list price, or the seller's own estimate.
- All-pay auction
- An auction in which every bidder pays, whether or not they win. A penny auction is one type. See also Dollar auction.
- Arbitration clause
- A term in an agreement that sends disputes to a private arbitrator instead of a court.
- Ascending auction
- The most familiar format: bidders raise the price openly until no one bids higher.
- Auto-bidder
- A site tool that places bids for you automatically, up to a number of bids you set. Each automatic bid still costs a bid.
B
- Beginner auction
- An auction open only to bidders who have won few or no auctions.
- Bid
- One action that raises the auction price by one price step and adds time to the clock. In a penny auction, each bid uses one paid bid credit.
- Bid agent
- A person or tool that bids on your behalf. It can be someone you authorize to bid for you, a site's automatic bidding tool, or a proxy-bidding system. See also Auto-bidder and Maximum bid.
- Bid credit
- A unit you buy in advance and spend to place one bid. Also simply called a "bid."
- Bid expiration
- A rule that removes unused bids from your account after a set time.
- Bid increment
- The minimum amount by which a new bid must beat the current one.
- Bid pack
- A bundle of bid credits sold together, either at a set price or as the prize of an auction.
- Bid-refund auction
- An auction in which the winner gets part of their spent bids back, for example half.
- Bid shading
- Bidding less than an item is worth to you, to leave room for a saving if you win.
- Bid sniping
- Placing a bid in the final seconds of a fixed-end auction so others have no time to respond.
- Bid spending
- The total amount you spend on bids in an auction: number of bids placed × cost per bid.
- Bidder concentration
- How much of an auction's bidding comes from its few most active bidders.
- Bot
- Software that places bids automatically. When run by a site to pose as real bidders, it is a form of shill bidding. See also Collusion.
- Bundled bids
- Bid credits included in an auction's prize, sometimes alongside a product.
- Buy it now
- An option some sites offer to non-winners: buy the item at a set price, with the value of bids already spent credited toward it.
- Buy now price
- The fixed price at which a site offers to sell an item directly, outside the auction. In penny auctions it is usually the only price shown for an item, and non-winners may be able to apply the bids they spent toward it.
C
- Chargeback
- Reversing a card payment through your bank or card issuer. Using it to get money back for an item you did receive is fraud.
- Class-action waiver
- A term in an agreement that stops you from joining other customers in a group lawsuit.
- Closing price
- The auction price when the countdown reaches zero. The winner pays it in addition to their bid spending.
- Collusion
- Bidders secretly working together, for example agreeing not to bid against each other or placing fake bids to create activity.
- Cost per bid
- What one bid actually costs you: the bid pack's price divided by the number of bids in it.
- Countdown timer
- The clock that shows how long an auction has left. In a penny auction, each new bid resets or extends it.
D
- Descending auction
- The price starts high and drops until someone accepts it.
- Dollar auction
- An economics game from 1971 in which a dollar is auctioned and the top two bidders both pay, so bidding often goes past a dollar.
E
- Entertainment shopping
- A marketing label some sites use for penny auctions.
- Escalation of commitment
- Raising your stake to justify earlier decisions, even when the new spending is not worth it on its own.
F
- Fixed end time
- A set moment when an auction closes, regardless of bidding activity.
- Free-to-bid auction
- An auction in which placing a bid costs nothing; you pay only if you win.
H
- Hammer price
- The final winning bid at an auction, before fees and taxes.
- Heavy bidder
- A participant who places a large share of an auction's bids.
I
- Increment
- See Price step.
L
- Late-entry limit
- A rule that closes an auction to new bidders after a set time or price. Only people who have already bid can continue.
- Loss chasing
- Spending more, for example in another auction, to try to win back money already lost.
- Lot
- An item, or group of items, sold as one unit in an auction.
- Lowest-unique-bid auction
- An auction where each bid costs money and the lowest amount bid by only one person wins.
M
- Market price
- What an item actually sells for through ordinary retailers at a given time.
- Maximum bid
- The highest amount you are willing to pay, entered in advance. The site bids for you in small steps up to that limit.
- MSRP
- Manufacturer's suggested retail price. A reference price set by the maker, not necessarily what shoppers pay.
- Multiple accounts
- One person running more than one account on a site, usually against its rules, for example to get around win limits.
N
- Near-win feeling
- The sense of having almost won, such as leading seconds before the end, which makes continuing feel more worthwhile than it is.
O
- One-yuan treasure hunt
- A lottery-style shopping format, popular in China until 2017, in which buyers purchase ¥1 shares of an item and one is drawn to win it.
- Opening bid
- The price at which bidding begins.
P
- Pay-per-bid auction
- Another name for a penny auction.
- Penny auction
- An online auction in which each bid costs a non-refundable fee, raises the price by a small step (usually one cent), and adds time to the clock. The last bidder when time runs out wins.
- Penny-price auction
- An auction in which the winner pays a fixed low price, often one cent, instead of the final auction price.
- Penny social
- A fundraiser where guests buy tickets and place them beside prizes, and one ticket per prize is drawn at random. Also called a basket raffle or tricky tray.
- Ponzi scheme
- A fraud that pays earlier investors with money from newer ones rather than from real profits.
- Power bidding
- Bidding instantly every time to signal you will never stop and push other bidders to give up.
- Price step
- The amount each bid adds to the auction price, usually $0.01 in a penny auction.
- Proxy bid
- See Maximum bid.
R
- Reserve price
- A hidden minimum price. If bidding does not reach it, the item does not sell.
- Retail value
- The standard price an item is sold for at retail, such as the MSRP or a retailer's list price. It may be higher than what the item actually sells for.
S
- Sealed-bid auction
- Each bidder submits one private bid, and the highest bid wins.
- Shill bidding
- Fake bids placed by, or on behalf of, the seller or site to push the price up or keep an auction going. It is deceptive and often illegal. See also Collusion.
- Stealth marketing
- Paid promotion presented as an independent opinion, such as a sponsored post that does not say it was paid for.
- Sunk cost
- Money already spent that cannot be recovered, such as bids used in an auction. Continuing to bid to "protect" sunk costs is a common trap. See also Sunk-cost fallacy.
- Sunk-cost fallacy
- Continuing something because of what you have already spent on it, even though that money is gone whatever you decide next. See also Sunk cost.
T
- Timer reset
- The time added to the countdown when someone bids, often 10 to 20 seconds.
- Total cost
- Everything the winner pays: bid spending + closing price + shipping and fees.
W
- Win limit
- A cap on how many auctions one person can win in a set period.
- Winner's curse
- Winning an auction by paying more than the item is actually worth.