What is bait-and-switch and how is it commonly used in marketing tactics?

Bait-and-switch is a deceptive marketing tactic where a business advertises a product or service at a low price to attract customers, but then tries to sell them a different, usually more expensive, item instead. This tactic is commonly used to lure customers in with a tempting offer and then upsell them on a different product once they are already interested.