What Is a Data Center and What Do Data Centers Do?

A data center is a secure building, or campus of buildings, that houses thousands of computer servers and keeps them powered, cooled and connected to the internet around the clock. That is what data centers do: they store data and run the apps, websites, cloud services and AI models people use every day. For job seekers, the key point is that a data center is mostly an electrical and mechanical plant with computers inside, which is why electricians, HVAC techs and facilities technicians make up a big share of the people who build and run them.

What do data centers do?

Every time you stream a show, send an email, pay with a card or ask an AI chatbot a question, a server somewhere does the work. Data centers are where those servers live. A company can own its data center, rent space in someone else’s, or buy computing from a cloud provider that runs huge data centers of its own.

The job of the building is simple to describe and hard to do: keep every server running 24 hours a day, 365 days a year. That means steady power with backups for the backups, enough cooling to carry away the heat the servers give off, fast network connections, and tight physical security. Downtime costs the owner money and customers, so almost everything inside is built with spare capacity.

How does a data center work?

Think of a data center as four systems wrapped around a room full of computers:

• Power comes in from the utility, gets stepped down and cleaned up, and is backed by batteries and generators.
• Cooling removes the heat that servers turn their electricity into.
• Network connects the servers to each other and to the outside world over fiber.
• Security and controls watch the building, the equipment and who comes and goes.

Operations staff monitor all of it from a control room, often called a NOC or a building operations center, using a building management system (BMS) for mechanical equipment and an electrical power monitoring system (EPMS) for the power side.

Inside a data center: the main spaces and systems

The white space (data halls)

The “white space” is the raised-floor or slab-floor room where the IT equipment sits. Large facilities split it into several data halls. Servers, storage and network gear are mounted in metal cabinets called racks, lined up in rows. Rows are usually arranged in hot aisles and cold aisles so cool air goes in the front of the servers and hot exhaust comes out the back, where it can be captured and removed.

Rack power has been climbing. Uptime Institute’s 2025 global survey of operators (July 2025) found more racks now fall in the 10 to 30 kW range, though racks above 30 kW are still uncommon in most facilities. AI racks are the big exception, and they drive many of the design changes described below.

The gray space: power

The “gray space” holds the equipment that supports the IT. On the power side, a typical path looks like this:

• Utility feed and substation: large campuses often get their own high-voltage substation, sometimes built on site.
• Transformers and switchgear: step voltage down and route power to different parts of the building, with breakers that can isolate faults.
• UPS (uninterruptible power supply) and batteries: keep servers running for the seconds or minutes between a utility outage and generator start-up, and filter out power quality problems.
• Diesel or gas generators: carry the building through longer outages. Big sites have rows of them, plus fuel storage.
• PDUs, busway and remote power panels: deliver power the last few feet to each rack.

This is high-voltage, high-consequence work. Switching errors can drop a data hall, so procedures, lockout/tagout and method-of-procedure (MOP) documents are a big part of daily life for the electrical team.

Cooling

Servers turn almost all of the power they use into heat. Common cooling equipment includes:

• Chillers that make chilled water for the building.
• CRAHs and CRACs (computer room air handlers and air conditioners) that blow cool air through the data hall.
• Cooling towers and dry coolers on the roof or yard that reject heat outside.
• Pumps, piping and valves that move water and coolant around the site.
• Liquid cooling, including direct-to-chip cold plates and coolant distribution units (CDUs), which pipe liquid right up to the hottest chips.

Liquid cooling is spreading fast because AI chips run too hot for air alone. For example, Microsoft says more than 90% of its new AI data center in Mount Pleasant, Wisconsin, uses a closed-loop liquid cooling system (Microsoft, September 2025). That shift means more pipefitting, more water treatment and more mechanical work inside the white space than older data centers needed.

Network and fiber

Data centers connect to the outside world through fiber from carriers and internet exchanges, usually entering through a “meet-me room” where networks hand off traffic. Inside, structured cabling and fiber trays tie every rack to switches and routers. AI clusters need a huge amount of fiber: Microsoft says its Wisconsin site has enough fiber to wrap the planet four times (Microsoft, September 2025).

Security

Expect fences, gates, guard posts, cameras, badge readers, man-traps (two-door entry vestibules) and sometimes biometric scanners. Visitors and workers are logged in and escorted. Phones and cameras are often restricted on the data hall floor. These rules apply to everyone, including contractors, and they shape what a workday feels like.

Types of data centers

Type	Who owns or uses it	What it’s like to work at
Hyperscale	Large cloud and tech companies running their own massive campuses	Very large sites, highly standardized procedures, lots of construction activity
Colocation (“colo”)	A provider rents space, power and cooling to many tenants	Customer-facing work, many different tenants and their equipment
Enterprise	A single company (bank, hospital, government agency) for its own IT	Smaller teams, often wider job duties per person
Edge	Small sites placed close to users for speed	Often unstaffed; technicians travel between sites
AI-focused	Facilities built for dense GPU clusters	Higher power per rack, heavy liquid cooling, fast build schedules

Tiers and redundancy, briefly

You will hear people talk about “Tier III” or “Tier IV” sites. These come from the Uptime Institute’s Tier Classification System, which grades how well a facility’s design keeps IT running:

• Tier I (basic capacity): a UPS, dedicated cooling and a generator, but little spare equipment.
• Tier II (redundant capacity components): extra UPS modules, chillers, pumps and generators.
• Tier III (concurrently maintainable): any component can be taken offline for maintenance without shutting down the IT.
• Tier IV (fault tolerant): a single equipment failure or path interruption does not reach the IT.

You’ll also hear redundancy described as N, N+1 or 2N. “N” is the amount of equipment needed to run the load; N+1 adds one spare; 2N is a complete second set. For workers, more redundancy means more equipment to maintain and more careful switching procedures.

Why are so many data centers being built now?

Two things are driving the boom: the ongoing move of business software to the cloud, and the rapid growth of AI, which needs far more computing power and electricity per rack than traditional workloads.

The power numbers show the scale. A U.S. Department of Energy report prepared by Lawrence Berkeley National Laboratory (December 2024) found data centers used about 4.4% of U.S. electricity in 2023, or about 176 terawatt-hours, up from 58 TWh in 2014. It projected data centers could use roughly 6.7% to 12% of U.S. electricity by 2028, between about 325 and 580 TWh.

The construction wave shows up in jobs data too. A PwC study for the Data Center Coalition (May 2026) estimated that jobs supported by data center capital spending rose 56% in one year, from about 1.1 million in 2023 to about 1.7 million in 2024. Those figures include indirect and induced jobs across the economy, not only workers on job sites, but they point in the same direction: a lot of building is going on.

Which jobs map to each system?

Every system above needs people to build it, start it up and keep it running. Here is how the building lines up with the work:

System	Typical jobs	Job category
Power (switchgear, UPS, generators)	Electricians, critical facilities technicians and engineers, generator and UPS field service techs	Electrical and power
Cooling (chillers, CRAHs, liquid cooling)	HVAC technicians, pipefitters, mechanical engineers, controls/BMS techs	Mechanical, HVAC and cooling
Facility operations (24/7 monitoring)	Critical facilities technicians, shift leads, facility managers	Critical facilities operations
Servers and racks	Data center technicians, IT deployment techs, hardware repair	Data center technicians
Network and fiber	Fiber and low-voltage techs, network engineers	Low voltage, fiber and cabling
Building the site	Electricians, ironworkers, concrete crews, equipment operators, pipefitters, project managers, commissioning agents	Construction and building trades
Security	Security officers, safety and health professionals	Safety, health and security

Virginia’s Joint Legislative Audit and Review Commission (JLARC, December 2024) gives a useful picture of the split. It found that a single data center takes about 12 to 18 months to build, with about 1,500 workers on site at peak, while a typical finished 250,000-square-foot facility runs with about 50 full-time workers, roughly half of them contractors such as electricians, pipefitters and security staff. In other words, construction brings big crews for a limited time, and operations brings smaller teams for the long haul. If steady, long-term work appeals to you, browse critical facilities jobs. We break that down further in how many people work at a data center.

The trade-offs to know about

Data center work has real upsides: steady demand, modern equipment and, in operations, long-term roles. It also has downsides. Facilities run 24/7, so many operations jobs involve rotating or 12-hour shifts, nights and holidays. Data halls are loud, and security rules can feel strict. Construction work often means travel, long hours and moving from project to project as sites finish. Operators also report hiring pressure: nearly two-thirds of respondents to Uptime Institute’s 2025 survey said they struggle to retain staff, find qualified candidates, or both.

Next steps

Now that you know what is inside the building, the next question is which job fits you. Start with our overview of jobs at a data center, or go straight to open data center jobs near you.