Somewhere right now, a server is repricing the flight you looked at yesterday. Not because anything changed – no new fuel surcharge, no sudden spike in demand – but because you looked at it yesterday. The algorithm clocked that interest and nudged the number up a fraction to see what would happen. This is yield management, and once you know it exists you cannot unsee it.

The basic idea is this: airlines, hotels, insurers, and a growing number of supermarkets do not set a price and leave it there. They run a continuous production line. Feed in data about who's searching, when, from which device, at what time of day, and the line outputs a price in real time. That output changes constantly, the way a factory adjusts its conveyor speed when the warehouse fills up. The price is not what something is worth. It is what the system thinks you will pay, right now, given everything it currently knows about you.

The Factory's Raw Materials

What goes in? Demand signals, mostly. How many people have viewed this route in the last hour, how far out the travel date is, whether the browser you're using is a Mac (genuinely, some pricing engines have historically charged more to Apple users, betting on higher average incomes). Whether you've visited the page before. Time of day matters too – early Tuesday morning is famously dead for leisure searches, so prices often dip then simply because the factory has too much stock and not enough interested buyers.

This is where the "book on Tuesday" folk wisdom actually comes from. It is not magic. It is a factory running slow because fewer people are shopping.

What The Factory Is Actually Optimising For

It is not trying to find a fair price. It is trying to fill every seat, room, or policy at the highest price each individual buyer will accept – a concept called price discrimination, which sounds sinister but is really just the factory squeezing its yield. Empty plane seats at take-off represent pure waste to this system, so when the factory detects unsold inventory close to departure, it discounts. That's also a real thing, and understanding it means you can use it: last-minute flight deals are not generosity, they're the factory panicking about waste.

For insurance, the same logic runs in reverse. New customers get cheap quotes because the factory is buying market share, while loyal customers get quietly repriced upward because the system has learned they probably won't switch. The fix is mechanical: shop your car or home insurance every single renewal. Be disloyal. The factory rewards it.

How do you stop a site tracking your searches?

Clear your cookies or use a private browsing window before you search for flights and hotels. You remove some of the personal data the factory runs on, and you occasionally see a lower starting price. Search the same routes across different devices. Check prices at genuinely unpopular hours. For supermarket price-matching deals, the algorithms tend to reset early in the week, which is why Monday and Tuesday often surface better offers.

None of this requires spreadsheets or obsession. It just requires knowing that every price you see was manufactured – and that the factory, like any factory, has quieter shifts.