Dark patterns (deceptive design patterns) are interface elements designed to push users into decisions they would not make with full knowledge: pre-ticked consents, costs hidden until the last checkout step, a subscription easy to start and hard to cancel.
The most common patterns already have names. "Roach motel": entering a service takes a minute, leaving requires a phone call during office hours. Confirmshaming: a decline button worded to embarrass ("No, I prefer overpaying"). False urgency: countdowns and "only 2 left" messages with no basis in actual stock. Hidden costs: delivery and fees added only at the final checkout step.
Beyond the reputational damage, legal risk is growing: EU law, including the Digital Services Act (DSA), explicitly bans deceptive interfaces, and consumer protection authorities fine companies for practices such as fake promotion countdowns or obstructed subscription cancellation.
Why it matters for business: dark patterns lift results short-term and you pay for them later: in returns, complaints, public reviews and customers who felt cheated. Hunting for these spots is a standing part of an e-commerce UX audit, because some conversion "optimisations" turn out to be debt weighing on the brand.