A server is a computer, or a program running on a computer, that provides a service to other devices over a network. When you open a website, send an email or join an online game, your device (the client) sends a request and a server answers it. This guide explains what a server is, what makes server hardware different, and the server types you will meet when you buy hosting.
What is a server, exactly?
The word "server" has two meanings that are used interchangeably:
- Server software – a program that listens for requests and answers them, for example Apache or LiteSpeed (web), Exim or Postfix (email) and MySQL or MariaDB (databases).
- Server hardware – the physical machine that runs that software, usually a rack-mounted computer in a data centre with redundant power, fast storage and a permanent internet connection.
One physical machine usually runs many server programs at once. A typical shared hosting server runs a web server, a mail server, a DNS server, a database server and an FTP server side by side.
How a client and server talk
- Your browser looks up the domain name through DNS and gets the server's IP address.
- It opens a connection to that IP on a port, such as 443 for HTTPS.
- The server software listening on that port reads the request, builds a response (an HTML page, an email, a database result) and sends it back.
- The connection closes or stays open for the next request.
The same pattern applies to every server type; only the protocol and port change.
How a server differs from a desktop PC
| Feature | Desktop PC | Server |
|---|---|---|
| Runs | A few hours a day | 24/7, for years |
| Memory | Standard RAM | ECC RAM that corrects memory errors |
| Storage | One drive | Several drives in RAID, often NVMe |
| Power | One power supply | Redundant power supplies and UPS/generator backup |
| Management | Keyboard and screen | Remote access over SSH and out-of-band tools like IPMI |
| Network | Home broadband | Data-centre uplinks with static IP addresses |
Common server types
Web server
Serves websites over HTTP and HTTPS. Popular choices are Apache, Nginx, LiteSpeed, OpenLiteSpeed and Caddy. MdmHost hosting uses LiteSpeed.
Mail server
Sends, receives and stores email. An MTA such as Exim or Postfix moves mail between servers over SMTP, and Dovecot lets mail apps read mailboxes over IMAP and POP3.
DNS server
Translates domain names into IP addresses. Authoritative DNS servers (BIND, PowerDNS) hold your zone; resolvers look answers up for clients.
Database server
Stores structured data for applications. MySQL, MariaDB and PostgreSQL are the most common for websites.
File and FTP server
Stores files and lets users upload or download them over FTP, SFTP, SMB or NFS.
Application server
Runs application code such as Node.js, Python, PHP-FPM or Java, usually behind a web server or reverse proxy.
Game server
Keeps the shared state of a multiplayer game, such as Minecraft, and syncs it with every connected player.
Proxy and load balancer
Sits in front of other servers to forward, cache or spread traffic. Nginx, HAProxy and LiteSpeed can all act as reverse proxies.
Ways to rent a server
You rarely need to own hardware. Hosting comes in a few shapes:
- Shared hosting – your site shares one server with other customers and the host manages everything. See MdmHost web hosting.
- Reseller hosting – a slice of a shared server you can split into cPanel accounts for clients.
- VPS – a virtual machine with its own operating system and root access.
- Dedicated or bare-metal server – a whole physical machine for one customer.
- Cloud server – a VPS that runs on a cluster and can be resized or moved quickly.
For a side-by-side comparison read hosting types compared.
FAQ about servers
Can my own computer be a server?
Yes, any computer can run server software, but home connections usually have dynamic IPs, blocked ports and no redundancy, so they are only good for testing.
Is a server the same as hosting?
Hosting is a service built on servers: the provider runs and maintains the server and rents you space or a whole machine on it.
Which server type does a website need?
At minimum a web server and usually a database server. Shared hosting includes both, plus email and DNS, already set up.
What operating system do servers use?
Most web servers run Linux distributions such as AlmaLinux, Rocky Linux, Ubuntu or Debian; Windows Server is used for .NET and Microsoft workloads.