What is a server?
A server waits for a request and returns a response, such as a page, an email, a database row, or a file. The word names a role, not a hardware brand. That role can run in a data centre or on a PC for a test. Hosting decides who else shares the box and who patches it.
- It waits for a request and sends a response.
- The response can be a page, mail, a query, or a file.
- The role can run on data-centre hardware or, for a test, on a PC.
- Hosting is the decision about sharing, patching, and the address.
What types of servers are there, from web and mail to database, file, game, and DNS?
Servers are named for the service they answer: web for HTTP, mail for email, database for queries, file for shared files, game for a match, and DNS for name lookups. One machine can run several. The web server page owns that subtype. Here, web is only one row in the list of roles.
| Role | What it answers |
|---|---|
| Web | HTTP requests for pages and APIs |
| Sending and receiving email | |
| Database | Stored queries and records |
| File | Shared files |
| Game | A match or world for players |
| DNS | Name lookups |
One operating system can run more than one role. The HTTP role alone is what a web server is. This page does not repeat that explanation.
How do physical, virtual, and cloud servers differ?
A physical server is one machine, and its operating system is not shared with another customer. A virtual server is a slice with its own operating system. A cloud server is a virtual machine sold by CPU, memory, and disk. Cloud and VPS are both virtual. You tell them apart by how you resize and replace the slice.
| Physical | Virtual | Cloud | |
|---|---|---|---|
| Machine | The whole computer | A slice with its own OS | A virtual machine sold by size |
| Share the OS | No, not with another customer | No, the slice is yours | No, the slice is yours |
| How you change it | Hardware change | Resize within the host | CPU, memory, and disk as quoted |
How does a server differ from a desktop computer?
A desktop expects a person, a lid, and updates that may reboot at a bad moment. A server is built to stay on and keep a stable network address. Server software will run on a desktop for a test. Do not publish a site that way. When the PC sleeps, the site goes with it.
- A desktop is allowed to sleep. A public site cannot.
- A server is expected to keep a stable address.
- Desktop updates may reboot whenever they like.
- Using a PC as a test server is fine. Publishing on it is not.
Which server does a website need?
A website needs software answering HTTP on a machine that stays online. A small site can share the machine. Root or a private kernel means a virtual server. A size chosen by CPU, memory, and disk means cloud hosting. The whole machine for one customer means a dedicated server. One physical box for one tenant is bare metal.
Read what VPS hosting is when the site needs root. Read what a dedicated server is when one customer takes the whole machine. Read what a bare metal server is for the single-tenant physical case. Sized CPU, memory, and disk are cloud hosting. A small site can still share a machine.