NFTs are listed on Foundation in a reserve auction format.
Once the reserve price has been met, a 24-hour countdown for the auction begins.
If a bid is placed within the last 15 minutes of an auction, the countdown will reset back to 15 minutes. Time extensions can go on indefinitely until no other bids are placed within the last 15 minutes of an auction.
The addition of 15-minute extensions give each buyer enough time to place a bid, and for the artwork to find its true market value.