Introduction The Cloud: The World''s Filing Cabinet Civilization has always run on data. Human history began when people developed the ability to speak. With the invention of language, people could share their ideas, experiences, wants, and needs. Progress accelerated as people developed the ability to write. Ideas spread more easily and accurately not just from person to per­ son, but from place to place. Then came the spark that created the flame of knowledge: the ability to store, retrieve, and share what people had written. A hall­ mark of the ancient world became the construction of libraries.1 These archives of documents and books meant that people could communi­ cate more readily not just across space, but across time, passing information from one generation to the next.

Centuries later, when Johannes Gutenberg invented the mechanical printing press, the flame became a fire that empowered writers and readers alike. That fire would sweep the world. The ensuing centuries pro­duced an explosion in commerce that was both cause and conse­ quence of increasing communication. By the early twentieth century, every office needed a facility to store documents. Rooms were filled with filing cabinets. While data has always been important to society, it has never played the role it does today. Even when trade slows or economies falter, data continues to grow at a steady pace. Some say that data has become the oil of the twenty­first century.

But that understates the reality. A century ago, automobiles, airplanes, and many trains ran on oil. Today, every aspect of human life is fueled by data. When it comes to modern civilization, data is more like the air we breathe than the oil we burn. Unlike oil, data has become a renewable resource that we humans can create ourselves. This decade will end with almost 25 times as much digital data as when it began. With artificial intelligence, or AI, we''re doing more with data than ever before. We call the digital infrastructure that supports this the cloud.

While its name sounds soft and fluffy, in truth the cloud is a fortress. Every time you look something up on your smartphone, you pull data from a mammoth data center--a modern­day marvel that almost no one gets to step inside. But if you''re lucky enough to visit a data center, you''ll better un­ derstand how the world now works. One of the best places to see the inner workings of the cloud is the world''s capital of apples. The tiny town of Quincy, Washington, sits roughly 150 miles east of Seattle off Interstate 90. Its location is no accident. Quincy is in the center of the state''s agricultural basin, perched near a steep gorge carved for millennia by the wide and roll­ ing Columbia River, the largest waterway in the western United States. The town is powered by a network of hydroelectric plants, including the Grand Coulee Dam, the largest power station in the United States.

It''s an ideal setting for what has become the world''s biggest consumer of electricity, the modern data center. A few blocks off Quincy''s main street, you''ll find a series of non­ descript buildings secured by tall fences and walls. Some are marked by the logos of today''s tech companies; others have no identification at all. The largest of these facilities is called the Columbia Data Cen­ ter, which is owned by Microsoft. It''s thrilling--and a bit eerie--to take in the sheer size of a data center. Our facilities in Quincy are no longer just a single building. They fill two data center campuses with more than twenty buildings, totaling two million square feet. Each building is the size of two foot­ ball fields and is big enough to house two large commercial airplanes.

This collection of buildings is home to hundreds of thousands of server computers and millions of hard disks, each of which is replaced with faster, more efficient models every three years. The best way to get a sense of the scale of a data center is to walk from its outer edge to its center. Sitting outside the walls of each building are some of the world''s largest electrical generators, ready to power up within seconds to ensure the data center doesn''t skip a beat if the region''s electrical grid goes down. Each generator stands more than twenty feet high and can power the equivalent of more than two thousand homes. The generators are connected to diesel fuel tanks that can keep the data center running off the grid for forty­eight hours, with refueling arrangements in place to keep the operations up well beyond if ever needed. In our newer operations, like the one in Cheyenne, Wyoming, the generators run on cleaner natural gas and provide backup power to the region''s grid. Dozens of these huge generators stand next to the data center buildings, ready in case there is a local outage from the hydroelectric power supplied by the Grand Coulee Dam. Inside each building, a string of large secure rooms operate as electrical substations, typically pulling power from the electrical grid at 230,000 volts before reducing it to 240 volts to power the data center''s computers.

These substation rooms are lined with rows of six­foot racks, each connecting five hundred or more batteries that look like what you''d find under the hood of your car. Every door to the room is bulletproof and every wall is fireproof, so a fire can''t spread from one room to another. A typical data center building has four or more of these rooms, and depending on the configuration, the building may house as many as five thousand batteries. They serve two purposes. First, electricity from the grid flows through the racks, keeping the batteries charged and circumventing a potential electri­ cal spike, so the flow of electricity to the computers remains smooth and constant. And in the event of a power outage, the batteries will keep the data center operating until the generators start up. Through another set of bulletproof doors and fireproof walls, an­ other airport­style metal detector manned by two uniformed guards stands between you and the inner sanctum of the complex. Only full­time Microsoft employees with their names on a preapproved list can go any farther.

As you enter a small receiving room, a steel door closes behind you. You wait, locked inside as security staff look you over through a camera before opening the next bulletproof door. Finally, you enter a cavernous room, a temple to the information age and cornerstone of our digital lives. A hushed hum welcomes you into the nerve center containing floor­to­ceiling racks filled with computers, lined up in a formation that extends beyond your line of sight. This massive library of steel and circuits contains servers each identical in footprint but containing its own unique volume of data. It is the digital world''s filing cabinet. Somewhere in one of these rooms in one of these buildings, there are data files that belong to you. They have the email you wrote this morning, the document you worked on last night, and the photo you took yesterday afternoon.

They also likely contain personal in formation from your bank, doctor, and employer. The files occupy just a tiny sliver of a hard drive on one of these thousands and thou­ sands of computers. Each file is encrypted, meaning that the infor­mation is encoded so that only authorized users of that data can read it. Each data center building contains multiple rooms like this, sealed off from one another in case of fire. Each set of computers is connected to three power sources within the building. And each row is designed to recirculate throughout the building the heat given off by its computers to reduce the need for heating and hence electrical demand in the winter. As you leave the server room, you endure the entire security routine yet again. Off come your shoes and then your belt.

Just as you pause and consider the fact that you don''t have to endure this to leave an airport, your host reminds you that there is security in both direc­tions for a reason. Microsoft wants to ensure that no one can copy data on a thumb drive or steal a hard disk with someone''s personal data. Even the hard disks themselves leave through a special exit. When it''s time to replace them, their data is copied to a new com­ puter and the files are erased. Then the retired hard disk goes through the huge metal equivalent of a shredding machine. In some ways, the most remarkable feature is saved for the end of the tour. Your guide explains that each data center region has another set of buildings like this one, so the data of a business, government, or nonprofit can constantly be backed up somewhere else. This way, if there is an earthquake, hurricane, or some other natural or man­ made disaster, the second data center will step in to keep your cloud service operating smoothly.

As we found when an earthquake rocked northern Japan, our data center in southern Japan ensured there was no interruption of service. Today Microsoft owns, operates, and leases data centers of all sizes in more than 100 locations in more than 20 countries (and growing), delivering 200 online services and supporting more than a billion customers in more than 140 markets. When I joined Microsoft in 1993, one didn''t need much capital to start a software company. Bill Gates and Paul Allen, our two cofound­ ers, were the latest in a line of tech developers who had launched their companies from a garage or a college dorm room. The point was that the creation of software didn''t require a lot of money. A good computer, a small savings account, and a willingness to eat a lot of pizza were enough to get you started.