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Auction Basics

Auction Terms & Glossary

Auction listings can use terminology that isn't always obvious to a new bidder. This glossary explains common online-auction terms in plain English — bidding terminology, fees, reserve prices, auction lots, condition language, shipping and closing rules. Exact definitions and procedures can vary by platform, auction house and jurisdiction, so always read the terms for the specific auction you're entering.

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Essential Auction Terms Every Bidder Should Know

Buyer's Premium

An additional charge that may be assessed to the winning bidder according to the auction terms, generally calculated as a percentage of the winning bid . There is no universal percentage — the amount and calculation method depend on the individual auction, and some sales charge none at all.

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Reserve Price

A minimum threshold established under an auction's terms that generally must be reached before the item can be sold. If bidding does not reach the reserve, the seller may not be obligated to complete the sale, depending on the auction's rules.

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Proxy Bid

A bidding mechanism that may allow a bidder to enter a maximum amount while the system places bids on their behalf according to its rules — generally increasing the active bid only as needed up to the maximum. Exact behavior, including how ties and increments are handled, varies by platform.

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Maximum Bid

The highest amount a bidder authorizes the system to bid up to under a proxy or automatic bidding system. Entering a maximum bid does not necessarily mean you pay that amount — you may win at a lower active bid if competition stops earlier.

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Bid Increment

The amount by which the next acceptable bid must increase under the auction's rules. For example, if the current bid is $100 and the increment is $10, the next bid may need to be at least $110. Increments may be fixed, or they may change at different price levels — for instance, larger increments at higher prices. Always check the platform's published increment schedule.

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Lot

An individual item or a group of items offered together as one auction unit. A single lot may contain one object or many — read the description to understand exactly what is included before bidding.

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A

A

10 terms

  • Absentee Bid

    Also called: order bid, mail bid
    A bid submitted before an auction closes — or before a live sale begins — without the bidder participating in real time. The auction or platform applies the bid according to its own rules, which may resemble proxy bidding or may simply be a single fixed amount.

    Systems and terminology vary. Some platforms call this an "order bid" or "mail bid," and the way competing absentee bids are handled depends on the specific auction.

  • Absolute Auction

    Commonly refers to an auction conducted without a seller reserve, so the item sells to the highest bidder regardless of the final amount, subject to the specific auction terms and applicable requirements. Confirm the auction is truly "absolute" before assuming there is no reserve.

  • Appraisal

    A document or opinion estimating the value of an item, often prepared by a qualified professional. An appraisal is not automatically equivalent to market value or a guarantee of what the item will sell for, and it does not by itself establish authenticity.

  • As Is

    Indicates that the item is being offered in its present condition under the auction terms. This is not a universal waiver of every possible buyer right — the exact legal effect depends on the auction's terms and applicable law. See also As Is, Where Is.

  • As Is, Where Is

    A phrase that may indicate the buyer accepts the item's present condition and location according to the auction terms — meaning the buyer is responsible for collecting the item from where it sits. Exact legal effect varies by jurisdiction and the specific terms.

  • Auction

    A method of sale involving competitive bidding under established rules, where the price is determined by the bidders rather than set in advance by the seller.

  • Auction House

    An organization or business that conducts auctions. An online platform and an auction house are not necessarily the same entity — a platform may host sales run by many independent auction houses, each setting its own terms.

  • Auctioneer

    The person or organization conducting or managing the auction, depending on context. In an online sale, the auctioneer running each individual sale — not the platform — typically sets the terms you actually bid under.

  • Authentication

    The process of verifying that an item is what it is represented to be. Authentication may rely on maker's marks, documentation, provenance, or independent expert opinion. No single type of evidence universally proves authenticity.

  • Auto Bid

    Also called: automatic bid
    A term some platforms use for proxy or maximum bid functionality. Because terminology varies, treat "auto bid" as describing a similar concept rather than an identical system across every platform — check the platform's own definition.
B

B

4 terms

  • Bid

    An offer to buy an item at a stated amount, made according to the auction's rules. A bid may create a binding purchase obligation under the auction's terms and applicable law, so bidders should understand those terms before participating.

  • Bid Increment

    Also called: increment
    The amount by which the next acceptable bid must increase under the auction's rules. For example, if the current bid is $100 and the increment is $10, the next bid may need to be at least $110.

    Increments may be fixed, or they may change at different price levels — for instance, larger increments at higher prices. Always check the platform's published increment schedule.

  • Bidder

    A person or entity participating in the auction by placing bids. A bidder may need to register and meet eligibility requirements before being allowed to bid.

  • Buyer's Premium

    An additional charge that may be assessed to the winning bidder according to the auction terms, generally calculated as a percentage of the winning bid. There is no universal percentage — the amount and calculation method depend on the individual auction, and some sales charge none at all.
    Learn more: What Is a Buyer's Premium?
C

C

7 terms

  • Catalog

    The listing of lots offered in a sale, usually with descriptions and photographs. The catalog is your primary research tool — review it carefully before bidding.

  • Catalog Description

    The written description of a lot provided by the auctioneer. Descriptions may include maker, materials, measurements, condition and attribution language. Read the entire description rather than relying on the title alone.

  • Commission

    A fee or percentage that may be charged to the seller under their agreement with the auction company. A seller commission is separate from the buyer's premium and generally does not determine what the buyer owes unless specifically reflected in the auction terms.

  • Condition Report

    Information describing the observed condition of an item, which may be provided on request or as part of the listing. Scope and completeness vary — a condition report should not automatically be treated as an exhaustive guarantee that every defect has been identified.

  • Consignment

    Property entrusted to an auction company for sale. The consignor typically receives the proceeds minus any agreed commission or fees.

  • Consignor

    Also called: consigner
    The person or entity that consigns property to be sold at auction. The consignor is often (but not always) the seller, and is generally distinct from the auctioneer and the platform.

  • Current Bid

    The amount currently displayed as the leading bid or current auction price under the platform's rules. This is not necessarily the final amount owed — buyer's premiums, taxes, shipping and other charges may be additional.
E

E

2 terms

  • Estimate / Auction Estimate

    A stated estimate of expected auction value or selling range, where one is provided. An estimate is not a guarantee of selling price, market value, or future value. Items routinely sell above, below, or within their estimates depending on competition and condition.

  • Extended Bidding

    A system where bidding near the scheduled closing time may extend the auction, allowing additional bids rather than letting a last-second bid automatically end the competition. See also soft close. Not every platform uses this system.
H

H

2 terms

  • Hammer Price

    Also called: hammer
    Traditionally, the price at which bidding concludes for the lot — the moment the auctioneer "brings down the hammer." In online auctions, terminology may differ, but the concept generally refers to the successful bid amount before add-on charges.

    The hammer price generally does not automatically mean the total amount due. Buyer's premiums, taxes, shipping and other charges may be additional.

  • High Bidder

    The bidder currently holding the leading bid. Being the high bidder before the auction closes does not necessarily mean the item has been won — a reserve may not be met, or other bidders may still outbid you before closing.
I

I

1 term

  • Inspection / Preview

    Also called: preview
    An opportunity to examine items before bidding, either in person or through additional photographs and information. Inspection is not universally offered — when it is available, buyers of expensive or mechanical items should consider using it.
L

L

3 terms

  • Live Auction

    An auction conducted in real time, with bids accepted as the sale progresses. Online bidding may be offered alongside a live sale (see simulcast auction).

  • Lot

    An individual item or a group of items offered together as one auction unit. A single lot may contain one object or many — read the description to understand exactly what is included before bidding.

  • Lot Number

    An identifier assigned to a lot, used to organize and reference items within a sale. Lot numbers typically indicate the order in which lots will be offered.
M

M

2 terms

  • Maximum Bid

    Also called: max bid
    The highest amount a bidder authorizes the system to bid up to under a proxy or automatic bidding system. Entering a maximum bid does not necessarily mean you pay that amount — you may win at a lower active bid if competition stops earlier.
    Learn more: What Is Proxy Bidding?

  • Minimum Bid

    A phrase that can mean different things depending on the auction. It may refer to the opening or starting amount, the minimum required for the next acceptable bid, or another platform-defined threshold.

    Do not automatically equate "minimum bid" with reserve price — they are not always the same thing. Check the platform's terminology.
N

N

1 term

  • No Reserve

    Generally describes an auction where there is no seller reserve price preventing a sale solely because bidding did not reach a predetermined reserve threshold. A no-reserve auction does not guarantee a bargain — competition can still drive the price well above the opening bid.
O

O

2 terms

  • Online-Only Auction

    An auction conducted entirely online, with no in-person bidding component. These are often timed auctions, though live online sales also exist.

  • Opening Bid

    Also called: starting bid
    The amount at which bidding begins. An opening bid is not necessarily the same as the reserve price — a low opening bid does not guarantee the seller will accept a low final price if a higher reserve applies.
P

P

6 terms

  • Paddle Number / Bidder Number

    An identifier assigned to a bidder. In traditional auctions this corresponds to a physical paddle raised to place a bid. Online systems may use account-based bidder IDs instead of physical paddles.

  • Passed / Passed Lot

    A lot may be recorded as unsold or "passed" when it does not sell under the auction's rules — for example, when a reserve is not met. Reasons and terminology vary, and a passed lot may be relisted later.

  • Pickup Window

    The specified period during which purchased property must be collected. This is especially important for estate, vehicle, equipment and local auctions, where items cannot simply be mailed. Missing the window can forfeit the item or trigger storage fees.

  • Preview

    See Inspection / Preview. A scheduled period before the auction during which lots may be examined. Availability and format vary by auction.

  • Provenance

    Documented or represented history of ownership or origin. Strong provenance may help establish context, but a provenance claim should be evaluated based on the documentation and evidence provided. Provenance does not automatically prove authenticity or value.

  • Proxy Bid

    Also called: automatic bid, auto bid
    A bidding mechanism that may allow a bidder to enter a maximum amount while the system places bids on their behalf according to its rules — generally increasing the active bid only as needed up to the maximum. Exact behavior, including how ties and increments are handled, varies by platform.
    Learn more: What Is Proxy Bidding?
R

R

5 terms

  • Registration

    The process of creating an account and becoming eligible to bid. Depending on the auction, registration may involve verifying contact information, agreeing to terms, providing a payment method, or obtaining approval. Registration does not obligate you to bid.

  • Relisting

    Offering a lot for sale again after it did not sell, was withdrawn, or was otherwise not completed. Terms, pricing and reserve may change on a relisted lot.

  • Reserve Met

    Indicates that the reserve threshold has been satisfied under the auction system. This does not mean the auction is necessarily finished — other bidders may continue, and bidding may run until the scheduled or extended closing.

  • Reserve Not Met

    Indicates bidding has not yet reached the reserve threshold. The current high bidder may be leading but has not necessarily secured the right to purchase. Do not assume the high bidder will automatically be offered the item afterward.

  • Reserve Price

    A minimum threshold established under an auction's terms that generally must be reached before the item can be sold. If bidding does not reach the reserve, the seller may not be obligated to complete the sale, depending on the auction's rules.
    Learn more: What Is an Auction Reserve Price?
S

S

6 terms

  • Sale Price

    The amount for which an item is sold. Depending on context, this may refer to the hammer price or to a total including additional charges. Check how the specific auction uses the term.

  • Seller

    The person or entity offering property for sale. The seller, the auctioneer, and the online platform may all be different parties — knowing who is actually conducting the sale helps you understand who sets the terms.

  • Shipping

    The process of sending a purchased item to the buyer. Not every auction ships — some require local pickup or buyer-arranged transport. Confirm shipping availability and cost before bidding, especially for large or fragile items.

  • Simulcast Auction

    An auction that runs live and online at the same time, allowing both in-person and remote bidders to compete in the same sale. Bidding rules and how the two channels interact depend on the auction.

  • Soft Close

    A closing method where bids received near the scheduled end may extend bidding by a set amount of time. This is designed to allow additional bidding rather than letting a last-second bid automatically end the competition. Exact timing rules vary by platform.

  • Starting Bid

    The amount at which bidding begins. See opening bid. A low starting bid does not necessarily mean a low final price, especially if a reserve applies.
T

T

3 terms

  • Tax

    Applicable taxes that may be added to a purchase. Tax treatment varies by jurisdiction, transaction and circumstances, and we do not provide tax advice. Review the auction's terms and applicable requirements for your situation.

  • Third-Party Shipping

    Shipping arranged through an independent shipper rather than the auction company itself. Some auctions provide a list of recommended shippers; others leave transportation entirely to the buyer. Confirm who arranges and pays for shipping before you bid.

  • Timed Auction

    An auction where lots are scheduled to close at designated times rather than being called live in real time. Extended bidding or a soft close may still apply when bids arrive near the closing time.
W

W

3 terms

  • Watchlist

    A feature offered by some platforms that lets users save or follow specific lots. Not every platform provides one, and a watchlist is only a tracking tool — it does not place a bid.

  • Winning Bid

    Also called: final bid
    The successful bid amount under the auction's closing rules. The winning bid may not equal the total amount due — buyer's premiums, taxes, shipping and other applicable charges may be added on top.

  • Withdrawn Lot

    A lot removed from the auction before sale. Reasons and rules vary — a lot may be withdrawn by the seller, the auctioneer, or due to a dispute or error.

Auction Terms Can Vary by Platform

Online auction platforms do not necessarily use identical terminology. "Maximum bid," "proxy bid," "automatic bid" and similar phrases may describe related concepts but operate differently depending on the platform.

Likewise, closing rules, bid increments, reserve behavior, payment rules and pickup or shipping rules can all vary. The specific auction's terms control the actual process — not the label a platform uses for a feature.

Five Terms to Check Before Every Auction

  1. Buyer's Premium

    It changes what you actually pay on top of the winning bid.

  2. Reserve Price

    It determines whether the item will actually sell at the current bidding level.

  3. Bid Increment

    It sets the minimum step between bids and affects how fast prices climb.

  4. Closing Rules

    Soft closes and extended bidding can change when — and whether — a last-second bid wins.

  5. Shipping / Pickup

    Logistics can add substantial cost and may require you to collect items in person.

Not Sure What a Listing Means?

If wording in an auction listing or terms is unclear, ask the auctioneer or seller for clarification before bidding where contact is available. Do not make assumptions about unfamiliar terminology when the bid may create a purchase obligation.

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Ready to Put the Terms Into Practice?

Now that you understand the terminology, learn how registration, bidding, fees, payment and pickup fit together in a typical online auction.

Learn How Online Auctions Work