Here's where things get interesting, though: If a particularly important passage is highlighted by multiple Inkling users, that information is stored on the cloud and is available for anyone reading the same textbook to come across.

Today, any data that is collected about us in one place or another — and for one reason or another — can be stored in a computer bank.

Inefficient harvesting, inadequate local transportation and poor infrastructure (基礎設施)mean that produce is frequently handled inappropriately and stored under unsuitable farm site conditions.

Stored underground in large salt caves in Louisiana, this stockpile is called the Strategic Petroleum Reserve, and currently contains over 600 million barrels of oil, roughly equivalent to one month's supply.

The problem relates to the way data is stored on large websites: While your personal computer only keeps one copy of a file, large-scale services like Facebook rely on what are called content delivery networks to manage data and distribution.

But once these plants use up their stored reserve or tap out the underground supply, they cease growing and start to die.

Co-author Amy Zanne thinks that users probably range from climate-change researchers wanting to estimate how much carbon is stored in biomass, to foresters looking for information on different grades of timber.

Energy to drive a steam locomotive can be stored in other materials besides water.

The gas can be stored under pressure in a tank.

The liquid is maintained above its melting point until steam is required, at which point the liquid is allowed to turn back into a solid, releasing its stored energy.