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ELI5 Yahaaa

Someone else's computer, in a shed

Where Is the Cloud?

The cloud is not in the sky. It is a very large building full of computers, with an enormous electricity bill.

1 You save aphoto to thecloud2 It travelsacross theinternet3 It lands on arack in a bigbuilding
A building, not a sky.
  1. Step 1 of 5

    It is a building you could drive to.

    The cloud icon onyour phone Rows of racks in anenormous shed

    Data centres are windowless sheds the size of several football pitches, filled with racks of computers, roaring with fans. Your photos are on a drive in one of them.

  2. Step 2 of 5

    Everything is kept several times over.

    Your file is writtenseveral timesUsually in more thanone buildingA failed drive isswapped without fussNothing is lost whenone dies

    Drives fail constantly at that scale, so every file is written to several machines, usually in different buildings. A fire in one building loses nobody's photos.

  3. Step 3 of 5

    Most of the electricity is for cooling.

    Electricity forcomputingthe actual workElectricity for coolingnearly as muchagainAll of it ends as heatcarried out tothe air

    Computers turn nearly all the electricity they use into heat. A data centre spends an enormous amount more simply moving that heat outside before the machines cook themselves.

  4. Step 4 of 5

    Distance is why it sometimes feels slow.

    A server in your cityunnoticeableA server on another continenta definite pause

    Even at the speed of light, a request to a building on another continent takes noticeable time. So companies keep copies close to their users, in dozens of places at once.

  5. Step 5 of 5

    It is convenient, and it is not yours.

    Keeping files in thecloudSafe from alost or brokenphoneBut on someoneelse'smachines

    Cloud storage means never losing a phone's photos and reaching them anywhere. It also means the files sit on a company's machines, under their rules and their outages.

    Some data centres are deliberately built in cold countries, or next to a river, purely to make the cooling cheaper.

The short version

The cloud is racks of computers in big cooled buildings, holding copies of your files and sending them over the internet.

Try it yourself

Turn off the internet and open a cloud photo album. What is missing was never really on your phone.

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