Technology

Some apps and websites earn much of their income from advertising.

Some products become more valuable the more people use them.

Imagine a town whose first footpath bends around a wet field.

A quantity can grow by adding the same amount at each step or by multiplying by the same factor.

When you tap a button in an app and something happens, you are standing on top of a tower you cannot see.

How can someone send a confidential message without first meeting the recipient to agree on a secret code?

Open a map on your phone and a blue dot appears.

Clean water in a tank must still reach the people who need it.

A zipper brings two edges of cloth together.

Password advice has changed.

A phone can detect a fingertip through a layer of glass.

A microwave oven does not heat every material in the same way.

Lifting machines existed long before Elisha Otis.

In June 1974, a pack of chewing gum was scanned at a supermarket in Troy, Ohio.

During the Second World War, repairs involving British and American equipment exposed a practical difficulty: fasteners made to different standards were not reliably interchangeable.

Internet traffic often arrives in bursts.

A digital picture can contain millions of color values.

A message crossing a noisy channel can change before it arrives.

An electronic-paper display can keep showing a page even when it is not using power.

When a large message crosses the internet, it can be divided into smaller units called packets.

A computer must coordinate countless changes in its circuits.

A file can change while it is stored or sent.

Suppose a library of digital documents contains millions of pages.

During a contactless payment, a card or phone comes very close to a reader at the checkout counter.

When a browser requests the same image repeatedly, downloading it from a distant server every time wastes time and network capacity.

A robot enters an unfamiliar warehouse.

A heavy public door may swing open easily and then close without slamming.

An automated rain gauge can measure a shower without holding all the water that falls into it.

A trail camera can watch a woodland path when no person is there.

A socket wrench can tighten a bolt without making a full circle.

An atomic clock does not count atoms, and its timekeeping does not depend on radioactive decay.

Jonas tested two lamps for growing herbs indoors.

A computer does not store a written character as ink or shape.

An induction cooktop can warm a pan without a glowing burner.

An ordinary microphone mainly responds to pressure changes traveling through the air.

A neighborhood team keeps an evacuation map in a shared digital project.

A three-dimensional printer begins with a digital model.

A software team releases a new version of an online service.

A cable has one kind of plug, but a screen has another port.

Two computers can share a cable and still fail to communicate.

A crop satellite does not see a field as a farmer does.

An infrared television remote sends messages using light that our eyes cannot see.

A group builds an air-quality sensor and publishes editable design files.

Many color screens build pictures from tiny parts called pixels.

After sign-in, a service may give a device a short-lived authentication token.

A prosthetic hand can use motors to move fingers from user signals.