Bait-and-switch is older than the web.
The web simply made the bait clickable.
A customer sees an attractive product, price, plan, or condition and begins the transaction because of that representation. After engagement, the advertised option turns out to be unavailable, unsuitable for reasons the seller already knew, or replaced by a different product or more expensive condition.
The Federal Trade Commission defines classic bait-and-switch advertising as promoting a product without a genuine intention to sell it in order to establish contact with the customer and induce the purchase of something else.
See the FTC’s Advertising FAQs.
The bait matters because it starts the transaction
By the time the switch appears, the customer may have already spent time comparing options, created an account, entered personal information, traveled to a store, begun an application, or progressed through several checkout screens.
That investment creates pressure to continue rather than restart the search.
The FTC’s dark-pattern taxonomy uses bait and switch more broadly for interfaces where a choice or interaction leads to an unexpected and undesirable outcome. One example is a user clicking what appears to be a close control and getting software downloaded instead. Another is receiving something materially different from what was originally advertised.
See the FTC’s Bringing Dark Patterns to Light.
Not every substitution is deception
Products genuinely sell out. Inventory changes. A customer may discover that another model fits better. A seller can recommend alternatives.
The key question is whether the original offer was honestly available on the represented terms and whether the customer is clearly told when those terms change.
A legitimate substitution says, in effect: the thing you wanted is no longer available; here are alternatives, and you are free to walk away.
A bait-and-switch strategy uses the original offer mainly to get the customer committed enough that walking away becomes less likely.
That distinction is why the first representation matters even if the final product is technically acceptable.
The customer did not begin evaluating the final offer from a neutral starting point.
They were pulled into the transaction by a different one.
A fair sales process can change course.
It should not need a decoy to get the customer through the door.