When listing on Flippa there are two options to chose from - classified or auction.
An auction has a limited duration and allows bids from anyone which are automatically accepted. When bids reach or surpass the reserve set by the seller, the auction closes and that bidder is the winning buyer. The listing then moves to payment.
Classifieds do not have an end date and so it enables buyers more time to to ask questions and perform due diligence. Buyers make offers on a listing that need to be manually accepted by the seller. The seller does not have to accept any offer they do not wish to. When a seller does accept an offer, the classified closes and that buyer 'wins' the listing. The listing then moves to payment. A classified format is recommended for higher value or more complex listings as sometimes auctions do not provide buyers with enough time to perform due diligence before purchase and therefore they may choose not to engage and make an offer.