What Is a Server? Definition & Simple Explanation
Without them, nothing really works: Servers make sure websites are accessible, emails arrive, and cloud services run smoothly. But what exactly is a server, and how does it actually function?
Read on to find out what a server is, how it works, the different types that exist, and how you can use or run one yourself.
Servers are central computers or services that provide data and features to other devices (called clients). This happens around the clock, often without you even noticing.
They follow a request-response principle: The client sends a request, and the server delivers the appropriate response, such as a website or a file.
Different server types handle specific tasks: Web servers deliver websites, mail servers handle emails, and database servers manage structured information (like customer data or orders).
In everyday life, servers are mostly invisible but constantly active: When you browse the web, stream shows, or shop online, they keep everything running smoothly in the background.
There are several ways to run a server: You can buy your own hardware and manage it yourself, rent a server from a hosting provider, or use cloud services that scale flexibly to meet your needs.
What Is a Server?
A server is a computer that provides data and services to other devices. Whenever you visit a website, send an email, or save a file to the cloud, a server is working somewhere in the background.
The term server comes from their function ('to serve'). Technically, it refers to both the hardware and software that provide resources to other devices on a network.
These devices and applications—such as computers and smartphones—send requests to the server to receive data or use its services. These devices are called clients. For example, your browser acts as a client when it requests a website from a server.
Server as Hardware and Software
Servers consist of both hardware and software. In terms of hardware, a server is a specialized computer, often housed in data centers. Its components, such as processors, RAM, and hard drives, are optimized for stability, speed, and reliability. These machines are designed to run continuously without interruption.
A server doesn't have to be a large computer. Even your smartphone can act as a server when it shares photos or files over Wi-Fi with other devices. What matters is the role it plays in the network, not the type of hardware.
The appropriate server software handles specific tasks such as delivering web pages, sending emails and providing files. Examples of server programs include web servers such as Nginx, database servers such as MySQL, and mail servers such as Postfix.
How Servers and Clients Communicate
Servers and clients communicate through protocols. The process usually follows the same pattern: The client makes a request (e.g., "Show me the website EXPERTE.com"), and the server responds with the appropriate content ("Here is the website EXPERTE.com"). The roles are clearly defined and don't change.
Depending on the type of request, the server uses different protocols to communicate. Here are the most important ones:
HTTP (Hypertext Transfer Protocol) is used to transfer web page content that you view in your browser. The encrypted version is called HTTPS and uses an SSL certificate to secure the connection.
SMTP (Simple Mail Transfer Protocol) is used for sending emails.
IMAP / POP3 are used to retrieve emails from a mail server. IMAP is ideal if you want to access your emails on multiple devices, while POP3 downloads messages locally to a single device.
FTP (File Transfer Protocol) allows you to upload or download files, such as when editing or publishing a website.
What Do You Need a Server For?
Servers are used whenever multiple users or systems need access to centrally stored data or services. This applies to virtually all IT applications:
Companies store files on file servers
Websites are delivered by web servers
Emails are sent and received through mail servers
Streaming services rely on powerful media servers
But a server doesn't just deliver content. It also manages access rights, protects sensitive data, and ensures that applications run reliably even under heavy load.
The Most Important Server Types at a Glance
Servers handle different tasks depending on their purpose. Here's an overview of the most common server types:
Web servers deliver websites to users. When you enter a web address in your browser, a web server provides the corresponding page, including text, images, and videos. It processes requests using the HTTP or HTTPS protocol and ensures that website content loads quickly and displays correctly.
Mail servers handle sending and receiving emails. They use different protocols: SMTP for sending and IMAP or POP3 for receiving. Mail servers temporarily store emails, route them to the right recipients, and ensure secure delivery, usually within seconds.
File servers provide centralized storage for files on a network. They allow multiple users to access shared documents, images, or videos. File servers are especially useful in businesses where they make collaboration easier.
Database servers manage structured data and respond to queries from programs or other servers. They're used wherever information needs to be accessed quickly, reliably, and from a central location. Examples include online stores, login systems, or booking platforms.
Print servers receive print jobs from multiple computers and route them to the correct printers. They manage print queues, control access permissions, and prevent conflicts. This is a huge help in larger networks.
A DNS server (Domain Name System) translates human-readable web addresses like EXPERTE.com into technical IP addresses where servers can actually be reached. Without DNS servers, you'd have to memorize IP addresses.
Proxy servers sit between your device and the target server. They handle tasks like caching content, filtering (for parental controls or company policies), or anonymization (protecting your IP address).
Game servers are designed specifically for multiplayer online games. They keep game content synchronized across all players, save game progress, and process player actions in real time.
What Features Must Servers Have?
Modern servers handle complex tasks, so the requirements are high. To function reliably, servers must meet certain standards:
Availability
A server must run around the clock, 365 days a year, without downtime. This is achieved through measures like redundant hardware components, automatic monitoring, and clear emergency plans that kick in quickly when needed.Performance
Servers must be able to process large amounts of data quickly, even when many clients send requests at the same time. This requires powerful processors, fast RAM, high-speed network connections, and sometimes specialized hardware like SSDs or GPUs.Security
To prevent unauthorized access and protect data, servers use firewalls, access restrictions, regular updates, and encryption. Only authorized users should have access, and data must be protected against misuse, tampering, and loss.Centralization
Servers enable centralized management of data and services with clearly defined access and organized data storage. This helps administrators keep an overview and makes it easier to maintain, back up, and expand systems.
How Do You Get a Server?
There are several ways to use or set up a server. The best option for your project depends on how much control you need, your technical expertise, and your budget.
Run Your Own Server
If you want complete control over your server, you can use your own hardware, such as an old PC, a NAS system, or a Raspberry Pi. This eliminates monthly costs, but setup and operation require significant technical knowledge.
Best for: tech-savvy users, home networks, developer setups, smart home hubs
full control over hardware and software
no dependence on third parties
affordable if you already have the hardware
high technical effort required
maintenance, security, and availability are your responsibility
electricity and internet costs can add up
Rent a Server (Hosting)
In most cases, the easiest option is to rent a server from a hosting provider. You can choose from different models, ranging from virtual servers (VPS) to dedicated machines.
If you don't want to handle updates and security yourself, you can choose managed hosting, where the provider takes care of the technical operations. There are also specialized options for specific applications, such as managed WordPress hosting.
Best for: businesses, website owners, agencies
no hardware purchase required
good availability and support from the provider
flexible, scalable performance
ongoing monthly costs
limited configuration options with some plans
quality and price vary widely depending on the provider
Using Cloud Servers
Cloud services like AWS, Microsoft Azure, or Hetzner Cloud let you spin up virtual servers on demand. With these cloud servers, you typically pay only for what you use. This makes them a great fit for dynamic projects with changing requirements.
Best for: startups, developers, and fast-growing businesses
servers ready to go in minutes
automatic scaling during traffic spikes
pay only for actual usage
technical complexity in setup and billing
ongoing costs can be difficult to predict
risk of vendor lock-in
Server Hosting Models at a Glance
If you decide to rent a server instead of running your own, you have several hosting models to choose from.
The following overview explains the most common models, how they work, their benefits, and approximate costs. This will help you find the model that fits your needs:
Server Type | Description | Typical Use Cases | Costs |
|---|---|---|---|
VPS (Virtual Private Server) | A VPS is a virtual private server that runs on shared hardware. It is isolated using software and has its own dedicated resources like RAM and CPU. |
| Low |
Cloud Server | A cloud server is a VPS within a cloud infrastructure where resources can be scaled flexibly. Cluster operation helps ensure high availability. |
| Medium |
Root Server | A root server gives you full administrator access. It can be a VPS or dedicated server where users manage the operating system and software themselves. |
| Medium |
Managed Server | A managed server is technically maintained by the provider. This includes updates, security patches, monitoring, and backups. |
| Medium |
Dedicated Server | A dedicated server is a physical server exclusively available to a single customer. There is no resource sharing with others. |
| High |
Bare-Metal Server | A bare-metal server is a non-virtualized, directly accessible server. It stands out for its high-performance and direct hardware control. |
| High |
Which Hosting Model Is Right for You?
The right server type depends on how much responsibility you want to take on, how much technical expertise you (or your team) have, and what your project requires.
Looking for a hassle-free server solution?
Managed servers are probably the easiest option for beginners and businesses without an in-house IT team. The hosting provider handles technical tasks like updates, security patches, monitoring, and backups. You can focus entirely on your content or applications.Want full control over your system?
Then root servers or dedicated servers are the way to go. You get full system access and set up everything yourself, from the operating system to the web server to the firewall. This option is best for experienced admins and tech-savvy users who know exactly what they're doing.Need maximum flexibility and scalability?
A cloud server is ideal when your requirements change quickly, such as with fluctuating visitor numbers or short-term projects. You can adjust resources like CPU power or storage at any time, and this often happens automatically.Planning a small web project or test environment?
Then a VPS might be the best solution. It combines low costs with solid performance but is less powerful than a dedicated server due to shared hardware.
Server Operating Systems: Linux and Windows
A server needs an operating system to function at all. Just like on your personal computer, it ensures that programs run, the network works, and data gets processed. It provides the technical foundation for all other services.
For most servers, two operating systems are especially common: Linux and Windows. They differ in usability, security, maintenance, and costs, and each has different strengths depending on the use case.
| Linux Server | Windows Server |
|---|---|---|
Costs | Open source, no license fees | Paid, license fees vary by version |
Flexibility | Highly flexible and freely customizable | More limited due to proprietary architecture |
Stability & Security | Very stable and secure, low maintenance | Regular updates, higher maintenance effort |
Resource Usage | Resource-friendly, ideal for web, mail, databases | Higher resource requirements |
Compatibility | Ideal for web servers, Docker, firewalls, etc. | Seamless integration with Microsoft services |
Target Audience | Tech-savvy users, developers, hosting providers | Businesses with Microsoft infrastructure |
Market Share | Dominant for web servers worldwide | Standard in many corporate networks |
If you work with Microsoft products or prefer a graphical user interface, Windows is a good choice. If you're planning web projects, want to use open-source tools, or need to keep costs low, Linux is the better option.
Both systems provide a stable foundation in professional environments. What matters most is your expertise, what you'll use the server for, and how your infrastructure is set up.
Conclusion: Servers as the Backbone of IT
Whether you're running a website, receiving emails, or streaming a movie, there's always a server working behind the scenes to make it happen. It delivers data, manages access, and keeps services running around the clock.
If you want to run your own server, you have plenty of options today. You can set up a home server, rent a hosting solution, or use flexible cloud services. The right choice depends on your goals, budget, and technical expertise.
Our comparisons of the best server and hosting solutions will help you find the perfect fit for your project.
